Focus 1 - AceHSC · selection and isolation accounts for adaptive radiation leading to divergent evolution and convergent evolution. • Darwin/Wallace theory outlines characteristics
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HSC Biology Core 2 ndash Blueprint of Life
Focus 1 Evidence of evolution suggests that the mechanisms of inheritance accompanied by selection allow change over many generations
Outline the impact on the evolution of plants and animals of
o changes in physical conditions in the environment o changes in chemical conditions in the environment o competition for resources
Changes in physical conditions in the environment bull Include natural conditions (eg Temperature availability of water)
bull Australian landmass has become drier over time
- Led to changes in species of kangaroos present today bull Approx 25 million years ago Aust wetter
- Large areas of rainforest - Kangaroos small omnivorous unspecialised teeth - Ate variety of foods from forest floor - Food nutritious abundant - No need for specialised grinding teeth
bull As Aust became more arid grass more dominant vegetation in some
areas - Environmental selective pressure resulted in larger kangaroos
favouring teeth suited to grass - High crested molars efficiently grind low-nutrition grass into digestible paste - Slicing pre molars no use became reduced from ancestral kangaroos
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Changes in chemical conditions in the environment
bull Chemicals can affect evolution - Eg Salt elements such as Fe (iron)
bull Parts of Aust have high salinity in soils - Range of salt tolerant plants evolved to inhabit these areas - Animals feeding on these plants also evolved to handle conditions
bull Sheep blowfly major problem in Aust sheep industry
- Stresses weakens lethal to sheep when larvae burrows into wounds amp wet wools
- Chemicals such as dieldrin amp organophosphates used to extensively used to control blowfly
- Genetic resistance occurred within fly population chemicals ineffective
- Withholding particular insecticide for a time allowed resistance blowfly population to drop
- Continued use of insecticide resulted in mutation of modifier gene increases maintains resistance
- Insecticides never effective again on this species regardless of number of generations passed
Competition for resources
bull Occurs within a species amp between species - If new species introduced into an area competition may lead to
different species using different resources
bull Resources include - Food - Shelter - Space - Mates - If species could specialise on different resources or breed at
different times they could avoid direct competition
bull Some fruit fly species evolved into different species confined to different type of fruit tree
- Possible if floweringfruiting times on each tree type suited to breeding cycles in fruit flies
- Eventually two separate species can result
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Describe using specific examples how the theory of evolution is supported by the following areas of study
o palaeontology including transitional forms o biogeography o comparative embryology o comparative anatomy o biochemistry
bull Palaeontology is the study of fossils - Fossils are preserved traces of life on Earth - Most are found in sedimentary rocks Also found in ice or amber - Include preserved body parts moulds casts of decayed organisms - Imprints left in mud (eg Footprints)
bull Preserved material lt10000 years old or hand made objects (eg Arrowheads) considered artefacts not fossils
Palaeontology
bull Fossil record provides time line of evolution of life engraved in order in which they appear in rock layers - Transitional fossils show gradual change in life forms over millions of years - Provide further evidence for evolutionary change
bull Transitional fossils with characteristics belonging to ancestral groups of interest - Demonstrate development of one group of organisms from another form or common ancestor - Help understand how evolutionary changes come about - Fossils record suggests modern vertebrates appeared in following order - Jawless fish 500mya - Bony fish 400mya - Amphibians 360mya - Reptiles 300mya - Birds 190mya - Mammals 150mya - Theory that they developed from common ancestor supported by fossil evidence - Intermediate types found show transition
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Eg - Most famous transitional form is Archaeopteryx - Fossil first thought to be a therapsid reptile - Reptilian features include - Teeth - Reptilian-like skeleton - Long jointed tail - Bird like features include - Feathers - Wishbone sternum to attach flight muscles - Wings - Provides evolutionary pathway between dinosaursreptiles amp birds Eg - Lung fish - Absorb O2 from air - Appeared 400mya - End of Devonian age - Thought amphibians developed from this line - Had bones in fins - May be able to walkdrag itself on land
Biogeography
bull Study of distribution of organisms over Earth - Distribution patterns provide evidence of species originating from common ancestors when isolated become new species
bull Earth has a number of biogeographical zones - Eg Arctic zone - Each with specific enviro features - Therefore contain organisms with specific adaptive features
bull Charles Darwin Alfred Russel observed distribution of species into different biographic regions - Saw as major evidence to support theory of evolution - Argued that animals in different regions come from ancestors in that region adapted to conditions overtime
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- Darwin suggested line (Wallacersquos Line) separate distribution of organisms of Asia amp Aust
bull Special Creation prevailing religious based explanation of the time - Didnrsquot explain why islands with similar conditions didnrsquot contain same flora amp fauna - Darwin proposed migration amp evolution much more satisfactory explanations for unique flora amp fauna in places such as Aust
Comparative Embryology
bull Study of embryos of different organisms - Looking for similarities differences - Similarities suggest common ancestry
bull Obvious similarities between embryos of fish amphibians reptiles birds mammals - Comparison of vertebrate embryos show all have gill slits even though they donrsquot remain later in life except in fish - Indicates fundamental step common to all vertebrates - Supports idea of a common ancestor
bull All chordates possess pharyngeal gill pouches at some stage in development
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Comparative Anatomy
bull Study of similarities differences in structure between different organisms - Similar structures evidence of common ancestry
bull Anatomical structures on different organisms that have same plan but different functions called homologous structures - Homologous structures evidence for evolution - Structures shared by related species because inherited some way from a common ancestor
o Eg of homologous structure - Pentadactyl limb found in amphibians reptiles birds mammals - Basic plan consists of 1 bone in upper limb 2 in lower limb leading 5 fingerstoes - In bats limb modified to form a wing with fingers extended skin stretched between each finger - Whales have fully formed pentadactyl limb within their single paddle like fin - Limbs are modified adaptations to different enviros - Suggests animals descended from common ancestors with pentadactyl limbs
o Eg Xylem - Ferns conifers flowering plants have vascular tissue
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Biochemistry
bull Some biochemical processes same for all living cells - Certain proteins common in a large number of organisms
bull Recent technology advances allowed comparison of organisms on molecular basis rather than structural - Previously impossible between distantly related species such as an orchid amp a mouse
bull Study of amino acid sequences shows that related species share more common sequences than unrelated species - Particular evidence derived form haemoglobin sequences showing humans amp rhesus monkey share all but 8 amino acid sequences (10) There are 125 amino acid differences between humans amp lampreys - Supports fossil embryological anatomical evidence that humans are more closely related to rhesus monkeys than lampreys
Explain how DarwinWallaces theory of evolution by natural selection and isolation accounts for adaptive radiation leading to divergent evolution and convergent evolution
bull DarwinWallace theory outlines characteristics favourable to reproduction amp survival of organisms in their environment will be selected for and over time new species will appear in response to environmental changes
bull Adaptive radiation - Refers to variety of different species evolved from ancestral lines as a result of migration amp isolation - DarwinWallace theory of natural selection amp isolation provides mechanism for adaptive radiation - If groups of a population become isolated chances are high that they will encounter differing selective pressure as each environment evolves independently - Eventually 2 populations may change enough to become 2 separate| species
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o Eg Biodiversity of flora fauna unique to Aust result of adaptive radiation - When Aust separated from Gondwana organisms evolved due to selective pressure from changing environment - Supports DarwinWallace theory of evolution
bull Adaptive radiation can lead to divergent evolution convergent evolution
- Divergent evolution - Occurs when closely related species experience different environments - Vastly different characteristics will be selected - Overtime species evolve differently appear quite differently - Eg Elephants large animals closely related to the hyrax small guinea pig like creature - Live amongst rocky outcrops on mountains - Comparison of skeletons indicates close relationship - Convergent evolution - Occurs when relatively unrelated species develop similar structures physiology behaviours in response to similar selective pressures from similar environments - Eg Dolphins (mammals) sharks (cartilaginous fish) evolved streamlined body shape amp fins enabling efficient movement in water - Only remotely related as vertebrates - Communal social behaviour developed independently in ants bees termites
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Plan choose equipment or resources and perform a first-hand investigation to model natural selection
bull lsquoStick birdrsquo a simple game using red amp green toothpicks - Red green toothpicks scattered over area on ground with a green background - One person in group given task of picking up as many toothpicks in given time - Count red toothpicks collected count green toothpicks collected - Repeat game on a neutral background - Collate results
bull More red toothpicks collected on green background because - Green toothpicks have physiological adaptation camouflage - Allows them to blend into background escaping predator - Natural selection has allowed green toothpicks to survive under selective pressure of predator - Red toothpicks will die out leaving green species to survive amp reproduce
bull Enviro selected better adapted lsquowormsrsquo to reproduce amp become greater in number - Green worms will become greater in number - Become prevalent phenotype within worm population
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Analyse information from secondary sources to prepare a case study to show how an environmental change can lead changes in a species
The Kangaroo - Kangaroos offer a unique opportunity to study evolutionary changes within a group of Australian mammals - Have best known fossil record most extensively studied of all Aust mammals - Have undergone rapid evolutionary change - Commonly good indicators of restricted enviros - Middle of Miocene (10-12 million ya) - Aust became warmer - Aust moved north - Aridity (dryness) increased - Rainfall became seasonal - Forests changed - Dominated by eucalypts - Some pockets of open forests - Grassland thriving in drier conditions - Kangaroos became abundant - Evolving to take advantage of variety of new environments emerging from changes - Dominated grasslands - Increased in size - Rapidly diversified - Kangaroos of this age show hopping - 5th toe adaptation to arboreal (live in trees) life lost - Fossils show adaptations to grazing life - Pliocene (5-2 million ya) - Continent continued to dry out at faster rate - Rainforest restricted to east coastal regions - Woodlands grasslands replaced rainforests in central Aust
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- End of Pliocene - Evolved bounding strides - Take advantage of vast grasslands in arid areas - Important adaptation - Pleistocene (16 million ya) to present - Kangaroos at most diverse - Varied from giant kangaroos to small types - Adapted to variety of enviros - Grasslands led to development of specialised teeth - Increased tempoC led to larger kangaroos
Use available evidence to Analyse using a named example how advances in technology have changed scientific thinking about evolutionary relationships
bull Technological changes - Up until 1950rsquos relationships between organisms worked out by - Anatomical similarities - Became possible to analyse protein sequence data amp DNA sequence data - Proteins (Eg Haemoglobin) compared amp similarities discovered based on biochemical similarities - Rate of change estimated - Possible to work out molecular clock - Estimates when 2 organisms shared common ancestors Eg Similarities between humans chimpanzees worked out by comparing amino acid sequences in DNA
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Analyse information from secondary sources on the historical development of theories of evolution and use available evidence to assess social and political influences on these developments
bull 1735 - Linnaeus - Published classification system - Humans apes classified together - No idea of evolution in classification though strongly contested
bull Late 1700s - Erasmus Darwin (grandpa Darwin) - Suggested life came from single source
bull 1809 - Lamarck - 1st theory of evolution - Variation developed due to lsquousersquo amp lsquodisusersquo - Changes passed onto offspring - Theory proved incorrect - Challenged creationism - Helped Darwinrsquos ideas be recognised
bull 1859 - Darwin - Published lsquoOn the Origins of Species by Means of Natural Selection - In 1871 applied theory to humans in lsquoDescent of Manrsquo
bull Early 1900s - Scientists refined Darwinrsquos theory
bull Social political influences - Up until Darwinrsquos theory - Predominant Western view creationism - Diversity of living things created for enviro at same time by God in 6 days remain unchanged unrelated - Despite mounting evidence Darwinrsquos theory still rejected by religious groups - Darwinrsquos theory of descendants from apes caused political social outrage
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HSC Biology Core 2 ndash Blueprint of Life
Focus 2
Gregor Mendels experiments helped advance our knowledge of the inheritance of characteristics
Outline the experiments carried out by Gregor Mendel
bull Mendel studied heredity bull 1860rsquos Gregor Mendel
- Formulated principles of genetics - Through careful methodical experimentation with garden peas - Garden peas have short reproductive cycle - Easily distinguishable characteristics - Easy to grow
bull Bred each variety for 2 yrs ensure pure breeding bull Crossed 1 variety with another
- Observed result in next generation bull Mendel examined
- Flower colour - Purple or white - Flower position - Axial or terminal - Seed shape - Round or wrinkled - Seed colour - Green or yellow - Pod shape - Inflated or constricted - Pod colour - Green or yellow - Stem height - Tall or short
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bull Mendel needed to control fertilisation - Self fertilisation ensured - Placed bag over flowers made sure pollen from stamens lands on carpal of same flower - Cross fertilisation ensured - Cutting off stamens before pollen was produced - Dusting carpal with pollen from another plant - Increase reliability - Mendel used thousands of plants in each experiment
bull Mendel worked with true breeding plants - Self fertilising plants - Produced offspring identical to parents 1 Mendel cross fertilised 2 true breeding plants for 1 characteristic - Eg Tall plants crossed with short plants - Mendel named these parent generation (P1) 2 Offspring produced called F1 (1st filial) generation 3 F1 generation self fertilised cross fertilised to produce F2
generation bull Each of seven traits had
- Dominant factor - Recessive factor - When 2 true breeding plants crossed only DOMINANT factor appeared in F1 - Recessive factor appeared in F2 in ratio 31 - (dominant recessive) relationship
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Describe the aspects of the experimental techniques used by Mendel that led to his success
bull Mendel was successful because - Used peas - Easily grown - Reproduced rapidly - Selected easily observable characteristics - Strictly controlled fertilisation process - Used mathematics rigorously to analyse results - Used large number of plants - Studied traits that had 2 easily identified factors - Lucky because each trait on separate chromosome - No crossing over occurred - Not sex-linked characteristics
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Describe outcomes of monohybrid crosses involving simple dominance using Mendels explanations
bull Monohybrid crosses involve 1 factor only - Eg Cross may involve a true breeding (homozygous) tall with a true breeding (homozygous) short plant - Produces a F1 generation where all plants are tall - Mendel explained F1 generation trait as a DOMINANT factor - Mendel explained observable ratios - Parents Homozygous tall homozygous short - F1 ALL TALL - F2 3 TALL 1 SHORT - Mendalian ratio (monohybrid ratio) 31
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Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
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Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
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Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
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Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
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Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
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HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
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each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
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Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
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Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
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Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
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Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
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Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
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XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
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Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
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Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
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- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
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Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
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Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
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bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
2 of 12
Changes in chemical conditions in the environment
bull Chemicals can affect evolution - Eg Salt elements such as Fe (iron)
bull Parts of Aust have high salinity in soils - Range of salt tolerant plants evolved to inhabit these areas - Animals feeding on these plants also evolved to handle conditions
bull Sheep blowfly major problem in Aust sheep industry
- Stresses weakens lethal to sheep when larvae burrows into wounds amp wet wools
- Chemicals such as dieldrin amp organophosphates used to extensively used to control blowfly
- Genetic resistance occurred within fly population chemicals ineffective
- Withholding particular insecticide for a time allowed resistance blowfly population to drop
- Continued use of insecticide resulted in mutation of modifier gene increases maintains resistance
- Insecticides never effective again on this species regardless of number of generations passed
Competition for resources
bull Occurs within a species amp between species - If new species introduced into an area competition may lead to
different species using different resources
bull Resources include - Food - Shelter - Space - Mates - If species could specialise on different resources or breed at
different times they could avoid direct competition
bull Some fruit fly species evolved into different species confined to different type of fruit tree
- Possible if floweringfruiting times on each tree type suited to breeding cycles in fruit flies
- Eventually two separate species can result
3 of 12
Describe using specific examples how the theory of evolution is supported by the following areas of study
o palaeontology including transitional forms o biogeography o comparative embryology o comparative anatomy o biochemistry
bull Palaeontology is the study of fossils - Fossils are preserved traces of life on Earth - Most are found in sedimentary rocks Also found in ice or amber - Include preserved body parts moulds casts of decayed organisms - Imprints left in mud (eg Footprints)
bull Preserved material lt10000 years old or hand made objects (eg Arrowheads) considered artefacts not fossils
Palaeontology
bull Fossil record provides time line of evolution of life engraved in order in which they appear in rock layers - Transitional fossils show gradual change in life forms over millions of years - Provide further evidence for evolutionary change
bull Transitional fossils with characteristics belonging to ancestral groups of interest - Demonstrate development of one group of organisms from another form or common ancestor - Help understand how evolutionary changes come about - Fossils record suggests modern vertebrates appeared in following order - Jawless fish 500mya - Bony fish 400mya - Amphibians 360mya - Reptiles 300mya - Birds 190mya - Mammals 150mya - Theory that they developed from common ancestor supported by fossil evidence - Intermediate types found show transition
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Eg - Most famous transitional form is Archaeopteryx - Fossil first thought to be a therapsid reptile - Reptilian features include - Teeth - Reptilian-like skeleton - Long jointed tail - Bird like features include - Feathers - Wishbone sternum to attach flight muscles - Wings - Provides evolutionary pathway between dinosaursreptiles amp birds Eg - Lung fish - Absorb O2 from air - Appeared 400mya - End of Devonian age - Thought amphibians developed from this line - Had bones in fins - May be able to walkdrag itself on land
Biogeography
bull Study of distribution of organisms over Earth - Distribution patterns provide evidence of species originating from common ancestors when isolated become new species
bull Earth has a number of biogeographical zones - Eg Arctic zone - Each with specific enviro features - Therefore contain organisms with specific adaptive features
bull Charles Darwin Alfred Russel observed distribution of species into different biographic regions - Saw as major evidence to support theory of evolution - Argued that animals in different regions come from ancestors in that region adapted to conditions overtime
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- Darwin suggested line (Wallacersquos Line) separate distribution of organisms of Asia amp Aust
bull Special Creation prevailing religious based explanation of the time - Didnrsquot explain why islands with similar conditions didnrsquot contain same flora amp fauna - Darwin proposed migration amp evolution much more satisfactory explanations for unique flora amp fauna in places such as Aust
Comparative Embryology
bull Study of embryos of different organisms - Looking for similarities differences - Similarities suggest common ancestry
bull Obvious similarities between embryos of fish amphibians reptiles birds mammals - Comparison of vertebrate embryos show all have gill slits even though they donrsquot remain later in life except in fish - Indicates fundamental step common to all vertebrates - Supports idea of a common ancestor
bull All chordates possess pharyngeal gill pouches at some stage in development
6 of 12
Comparative Anatomy
bull Study of similarities differences in structure between different organisms - Similar structures evidence of common ancestry
bull Anatomical structures on different organisms that have same plan but different functions called homologous structures - Homologous structures evidence for evolution - Structures shared by related species because inherited some way from a common ancestor
o Eg of homologous structure - Pentadactyl limb found in amphibians reptiles birds mammals - Basic plan consists of 1 bone in upper limb 2 in lower limb leading 5 fingerstoes - In bats limb modified to form a wing with fingers extended skin stretched between each finger - Whales have fully formed pentadactyl limb within their single paddle like fin - Limbs are modified adaptations to different enviros - Suggests animals descended from common ancestors with pentadactyl limbs
o Eg Xylem - Ferns conifers flowering plants have vascular tissue
7 of 12
Biochemistry
bull Some biochemical processes same for all living cells - Certain proteins common in a large number of organisms
bull Recent technology advances allowed comparison of organisms on molecular basis rather than structural - Previously impossible between distantly related species such as an orchid amp a mouse
bull Study of amino acid sequences shows that related species share more common sequences than unrelated species - Particular evidence derived form haemoglobin sequences showing humans amp rhesus monkey share all but 8 amino acid sequences (10) There are 125 amino acid differences between humans amp lampreys - Supports fossil embryological anatomical evidence that humans are more closely related to rhesus monkeys than lampreys
Explain how DarwinWallaces theory of evolution by natural selection and isolation accounts for adaptive radiation leading to divergent evolution and convergent evolution
bull DarwinWallace theory outlines characteristics favourable to reproduction amp survival of organisms in their environment will be selected for and over time new species will appear in response to environmental changes
bull Adaptive radiation - Refers to variety of different species evolved from ancestral lines as a result of migration amp isolation - DarwinWallace theory of natural selection amp isolation provides mechanism for adaptive radiation - If groups of a population become isolated chances are high that they will encounter differing selective pressure as each environment evolves independently - Eventually 2 populations may change enough to become 2 separate| species
8 of 12
o Eg Biodiversity of flora fauna unique to Aust result of adaptive radiation - When Aust separated from Gondwana organisms evolved due to selective pressure from changing environment - Supports DarwinWallace theory of evolution
bull Adaptive radiation can lead to divergent evolution convergent evolution
- Divergent evolution - Occurs when closely related species experience different environments - Vastly different characteristics will be selected - Overtime species evolve differently appear quite differently - Eg Elephants large animals closely related to the hyrax small guinea pig like creature - Live amongst rocky outcrops on mountains - Comparison of skeletons indicates close relationship - Convergent evolution - Occurs when relatively unrelated species develop similar structures physiology behaviours in response to similar selective pressures from similar environments - Eg Dolphins (mammals) sharks (cartilaginous fish) evolved streamlined body shape amp fins enabling efficient movement in water - Only remotely related as vertebrates - Communal social behaviour developed independently in ants bees termites
9 of 12
Plan choose equipment or resources and perform a first-hand investigation to model natural selection
bull lsquoStick birdrsquo a simple game using red amp green toothpicks - Red green toothpicks scattered over area on ground with a green background - One person in group given task of picking up as many toothpicks in given time - Count red toothpicks collected count green toothpicks collected - Repeat game on a neutral background - Collate results
bull More red toothpicks collected on green background because - Green toothpicks have physiological adaptation camouflage - Allows them to blend into background escaping predator - Natural selection has allowed green toothpicks to survive under selective pressure of predator - Red toothpicks will die out leaving green species to survive amp reproduce
bull Enviro selected better adapted lsquowormsrsquo to reproduce amp become greater in number - Green worms will become greater in number - Become prevalent phenotype within worm population
10 of 12
Analyse information from secondary sources to prepare a case study to show how an environmental change can lead changes in a species
The Kangaroo - Kangaroos offer a unique opportunity to study evolutionary changes within a group of Australian mammals - Have best known fossil record most extensively studied of all Aust mammals - Have undergone rapid evolutionary change - Commonly good indicators of restricted enviros - Middle of Miocene (10-12 million ya) - Aust became warmer - Aust moved north - Aridity (dryness) increased - Rainfall became seasonal - Forests changed - Dominated by eucalypts - Some pockets of open forests - Grassland thriving in drier conditions - Kangaroos became abundant - Evolving to take advantage of variety of new environments emerging from changes - Dominated grasslands - Increased in size - Rapidly diversified - Kangaroos of this age show hopping - 5th toe adaptation to arboreal (live in trees) life lost - Fossils show adaptations to grazing life - Pliocene (5-2 million ya) - Continent continued to dry out at faster rate - Rainforest restricted to east coastal regions - Woodlands grasslands replaced rainforests in central Aust
11 of 12
- End of Pliocene - Evolved bounding strides - Take advantage of vast grasslands in arid areas - Important adaptation - Pleistocene (16 million ya) to present - Kangaroos at most diverse - Varied from giant kangaroos to small types - Adapted to variety of enviros - Grasslands led to development of specialised teeth - Increased tempoC led to larger kangaroos
Use available evidence to Analyse using a named example how advances in technology have changed scientific thinking about evolutionary relationships
bull Technological changes - Up until 1950rsquos relationships between organisms worked out by - Anatomical similarities - Became possible to analyse protein sequence data amp DNA sequence data - Proteins (Eg Haemoglobin) compared amp similarities discovered based on biochemical similarities - Rate of change estimated - Possible to work out molecular clock - Estimates when 2 organisms shared common ancestors Eg Similarities between humans chimpanzees worked out by comparing amino acid sequences in DNA
12 of 12
Analyse information from secondary sources on the historical development of theories of evolution and use available evidence to assess social and political influences on these developments
bull 1735 - Linnaeus - Published classification system - Humans apes classified together - No idea of evolution in classification though strongly contested
bull Late 1700s - Erasmus Darwin (grandpa Darwin) - Suggested life came from single source
bull 1809 - Lamarck - 1st theory of evolution - Variation developed due to lsquousersquo amp lsquodisusersquo - Changes passed onto offspring - Theory proved incorrect - Challenged creationism - Helped Darwinrsquos ideas be recognised
bull 1859 - Darwin - Published lsquoOn the Origins of Species by Means of Natural Selection - In 1871 applied theory to humans in lsquoDescent of Manrsquo
bull Early 1900s - Scientists refined Darwinrsquos theory
bull Social political influences - Up until Darwinrsquos theory - Predominant Western view creationism - Diversity of living things created for enviro at same time by God in 6 days remain unchanged unrelated - Despite mounting evidence Darwinrsquos theory still rejected by religious groups - Darwinrsquos theory of descendants from apes caused political social outrage
1 of 9
HSC Biology Core 2 ndash Blueprint of Life
Focus 2
Gregor Mendels experiments helped advance our knowledge of the inheritance of characteristics
Outline the experiments carried out by Gregor Mendel
bull Mendel studied heredity bull 1860rsquos Gregor Mendel
- Formulated principles of genetics - Through careful methodical experimentation with garden peas - Garden peas have short reproductive cycle - Easily distinguishable characteristics - Easy to grow
bull Bred each variety for 2 yrs ensure pure breeding bull Crossed 1 variety with another
- Observed result in next generation bull Mendel examined
- Flower colour - Purple or white - Flower position - Axial or terminal - Seed shape - Round or wrinkled - Seed colour - Green or yellow - Pod shape - Inflated or constricted - Pod colour - Green or yellow - Stem height - Tall or short
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bull Mendel needed to control fertilisation - Self fertilisation ensured - Placed bag over flowers made sure pollen from stamens lands on carpal of same flower - Cross fertilisation ensured - Cutting off stamens before pollen was produced - Dusting carpal with pollen from another plant - Increase reliability - Mendel used thousands of plants in each experiment
bull Mendel worked with true breeding plants - Self fertilising plants - Produced offspring identical to parents 1 Mendel cross fertilised 2 true breeding plants for 1 characteristic - Eg Tall plants crossed with short plants - Mendel named these parent generation (P1) 2 Offspring produced called F1 (1st filial) generation 3 F1 generation self fertilised cross fertilised to produce F2
generation bull Each of seven traits had
- Dominant factor - Recessive factor - When 2 true breeding plants crossed only DOMINANT factor appeared in F1 - Recessive factor appeared in F2 in ratio 31 - (dominant recessive) relationship
3 of 9
Describe the aspects of the experimental techniques used by Mendel that led to his success
bull Mendel was successful because - Used peas - Easily grown - Reproduced rapidly - Selected easily observable characteristics - Strictly controlled fertilisation process - Used mathematics rigorously to analyse results - Used large number of plants - Studied traits that had 2 easily identified factors - Lucky because each trait on separate chromosome - No crossing over occurred - Not sex-linked characteristics
4 of 9
Describe outcomes of monohybrid crosses involving simple dominance using Mendels explanations
bull Monohybrid crosses involve 1 factor only - Eg Cross may involve a true breeding (homozygous) tall with a true breeding (homozygous) short plant - Produces a F1 generation where all plants are tall - Mendel explained F1 generation trait as a DOMINANT factor - Mendel explained observable ratios - Parents Homozygous tall homozygous short - F1 ALL TALL - F2 3 TALL 1 SHORT - Mendalian ratio (monohybrid ratio) 31
5 of 9
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
3 of 12
Describe using specific examples how the theory of evolution is supported by the following areas of study
o palaeontology including transitional forms o biogeography o comparative embryology o comparative anatomy o biochemistry
bull Palaeontology is the study of fossils - Fossils are preserved traces of life on Earth - Most are found in sedimentary rocks Also found in ice or amber - Include preserved body parts moulds casts of decayed organisms - Imprints left in mud (eg Footprints)
bull Preserved material lt10000 years old or hand made objects (eg Arrowheads) considered artefacts not fossils
Palaeontology
bull Fossil record provides time line of evolution of life engraved in order in which they appear in rock layers - Transitional fossils show gradual change in life forms over millions of years - Provide further evidence for evolutionary change
bull Transitional fossils with characteristics belonging to ancestral groups of interest - Demonstrate development of one group of organisms from another form or common ancestor - Help understand how evolutionary changes come about - Fossils record suggests modern vertebrates appeared in following order - Jawless fish 500mya - Bony fish 400mya - Amphibians 360mya - Reptiles 300mya - Birds 190mya - Mammals 150mya - Theory that they developed from common ancestor supported by fossil evidence - Intermediate types found show transition
4 of 12
Eg - Most famous transitional form is Archaeopteryx - Fossil first thought to be a therapsid reptile - Reptilian features include - Teeth - Reptilian-like skeleton - Long jointed tail - Bird like features include - Feathers - Wishbone sternum to attach flight muscles - Wings - Provides evolutionary pathway between dinosaursreptiles amp birds Eg - Lung fish - Absorb O2 from air - Appeared 400mya - End of Devonian age - Thought amphibians developed from this line - Had bones in fins - May be able to walkdrag itself on land
Biogeography
bull Study of distribution of organisms over Earth - Distribution patterns provide evidence of species originating from common ancestors when isolated become new species
bull Earth has a number of biogeographical zones - Eg Arctic zone - Each with specific enviro features - Therefore contain organisms with specific adaptive features
bull Charles Darwin Alfred Russel observed distribution of species into different biographic regions - Saw as major evidence to support theory of evolution - Argued that animals in different regions come from ancestors in that region adapted to conditions overtime
5 of 12
- Darwin suggested line (Wallacersquos Line) separate distribution of organisms of Asia amp Aust
bull Special Creation prevailing religious based explanation of the time - Didnrsquot explain why islands with similar conditions didnrsquot contain same flora amp fauna - Darwin proposed migration amp evolution much more satisfactory explanations for unique flora amp fauna in places such as Aust
Comparative Embryology
bull Study of embryos of different organisms - Looking for similarities differences - Similarities suggest common ancestry
bull Obvious similarities between embryos of fish amphibians reptiles birds mammals - Comparison of vertebrate embryos show all have gill slits even though they donrsquot remain later in life except in fish - Indicates fundamental step common to all vertebrates - Supports idea of a common ancestor
bull All chordates possess pharyngeal gill pouches at some stage in development
6 of 12
Comparative Anatomy
bull Study of similarities differences in structure between different organisms - Similar structures evidence of common ancestry
bull Anatomical structures on different organisms that have same plan but different functions called homologous structures - Homologous structures evidence for evolution - Structures shared by related species because inherited some way from a common ancestor
o Eg of homologous structure - Pentadactyl limb found in amphibians reptiles birds mammals - Basic plan consists of 1 bone in upper limb 2 in lower limb leading 5 fingerstoes - In bats limb modified to form a wing with fingers extended skin stretched between each finger - Whales have fully formed pentadactyl limb within their single paddle like fin - Limbs are modified adaptations to different enviros - Suggests animals descended from common ancestors with pentadactyl limbs
o Eg Xylem - Ferns conifers flowering plants have vascular tissue
7 of 12
Biochemistry
bull Some biochemical processes same for all living cells - Certain proteins common in a large number of organisms
bull Recent technology advances allowed comparison of organisms on molecular basis rather than structural - Previously impossible between distantly related species such as an orchid amp a mouse
bull Study of amino acid sequences shows that related species share more common sequences than unrelated species - Particular evidence derived form haemoglobin sequences showing humans amp rhesus monkey share all but 8 amino acid sequences (10) There are 125 amino acid differences between humans amp lampreys - Supports fossil embryological anatomical evidence that humans are more closely related to rhesus monkeys than lampreys
Explain how DarwinWallaces theory of evolution by natural selection and isolation accounts for adaptive radiation leading to divergent evolution and convergent evolution
bull DarwinWallace theory outlines characteristics favourable to reproduction amp survival of organisms in their environment will be selected for and over time new species will appear in response to environmental changes
bull Adaptive radiation - Refers to variety of different species evolved from ancestral lines as a result of migration amp isolation - DarwinWallace theory of natural selection amp isolation provides mechanism for adaptive radiation - If groups of a population become isolated chances are high that they will encounter differing selective pressure as each environment evolves independently - Eventually 2 populations may change enough to become 2 separate| species
8 of 12
o Eg Biodiversity of flora fauna unique to Aust result of adaptive radiation - When Aust separated from Gondwana organisms evolved due to selective pressure from changing environment - Supports DarwinWallace theory of evolution
bull Adaptive radiation can lead to divergent evolution convergent evolution
- Divergent evolution - Occurs when closely related species experience different environments - Vastly different characteristics will be selected - Overtime species evolve differently appear quite differently - Eg Elephants large animals closely related to the hyrax small guinea pig like creature - Live amongst rocky outcrops on mountains - Comparison of skeletons indicates close relationship - Convergent evolution - Occurs when relatively unrelated species develop similar structures physiology behaviours in response to similar selective pressures from similar environments - Eg Dolphins (mammals) sharks (cartilaginous fish) evolved streamlined body shape amp fins enabling efficient movement in water - Only remotely related as vertebrates - Communal social behaviour developed independently in ants bees termites
9 of 12
Plan choose equipment or resources and perform a first-hand investigation to model natural selection
bull lsquoStick birdrsquo a simple game using red amp green toothpicks - Red green toothpicks scattered over area on ground with a green background - One person in group given task of picking up as many toothpicks in given time - Count red toothpicks collected count green toothpicks collected - Repeat game on a neutral background - Collate results
bull More red toothpicks collected on green background because - Green toothpicks have physiological adaptation camouflage - Allows them to blend into background escaping predator - Natural selection has allowed green toothpicks to survive under selective pressure of predator - Red toothpicks will die out leaving green species to survive amp reproduce
bull Enviro selected better adapted lsquowormsrsquo to reproduce amp become greater in number - Green worms will become greater in number - Become prevalent phenotype within worm population
10 of 12
Analyse information from secondary sources to prepare a case study to show how an environmental change can lead changes in a species
The Kangaroo - Kangaroos offer a unique opportunity to study evolutionary changes within a group of Australian mammals - Have best known fossil record most extensively studied of all Aust mammals - Have undergone rapid evolutionary change - Commonly good indicators of restricted enviros - Middle of Miocene (10-12 million ya) - Aust became warmer - Aust moved north - Aridity (dryness) increased - Rainfall became seasonal - Forests changed - Dominated by eucalypts - Some pockets of open forests - Grassland thriving in drier conditions - Kangaroos became abundant - Evolving to take advantage of variety of new environments emerging from changes - Dominated grasslands - Increased in size - Rapidly diversified - Kangaroos of this age show hopping - 5th toe adaptation to arboreal (live in trees) life lost - Fossils show adaptations to grazing life - Pliocene (5-2 million ya) - Continent continued to dry out at faster rate - Rainforest restricted to east coastal regions - Woodlands grasslands replaced rainforests in central Aust
11 of 12
- End of Pliocene - Evolved bounding strides - Take advantage of vast grasslands in arid areas - Important adaptation - Pleistocene (16 million ya) to present - Kangaroos at most diverse - Varied from giant kangaroos to small types - Adapted to variety of enviros - Grasslands led to development of specialised teeth - Increased tempoC led to larger kangaroos
Use available evidence to Analyse using a named example how advances in technology have changed scientific thinking about evolutionary relationships
bull Technological changes - Up until 1950rsquos relationships between organisms worked out by - Anatomical similarities - Became possible to analyse protein sequence data amp DNA sequence data - Proteins (Eg Haemoglobin) compared amp similarities discovered based on biochemical similarities - Rate of change estimated - Possible to work out molecular clock - Estimates when 2 organisms shared common ancestors Eg Similarities between humans chimpanzees worked out by comparing amino acid sequences in DNA
12 of 12
Analyse information from secondary sources on the historical development of theories of evolution and use available evidence to assess social and political influences on these developments
bull 1735 - Linnaeus - Published classification system - Humans apes classified together - No idea of evolution in classification though strongly contested
bull Late 1700s - Erasmus Darwin (grandpa Darwin) - Suggested life came from single source
bull 1809 - Lamarck - 1st theory of evolution - Variation developed due to lsquousersquo amp lsquodisusersquo - Changes passed onto offspring - Theory proved incorrect - Challenged creationism - Helped Darwinrsquos ideas be recognised
bull 1859 - Darwin - Published lsquoOn the Origins of Species by Means of Natural Selection - In 1871 applied theory to humans in lsquoDescent of Manrsquo
bull Early 1900s - Scientists refined Darwinrsquos theory
bull Social political influences - Up until Darwinrsquos theory - Predominant Western view creationism - Diversity of living things created for enviro at same time by God in 6 days remain unchanged unrelated - Despite mounting evidence Darwinrsquos theory still rejected by religious groups - Darwinrsquos theory of descendants from apes caused political social outrage
1 of 9
HSC Biology Core 2 ndash Blueprint of Life
Focus 2
Gregor Mendels experiments helped advance our knowledge of the inheritance of characteristics
Outline the experiments carried out by Gregor Mendel
bull Mendel studied heredity bull 1860rsquos Gregor Mendel
- Formulated principles of genetics - Through careful methodical experimentation with garden peas - Garden peas have short reproductive cycle - Easily distinguishable characteristics - Easy to grow
bull Bred each variety for 2 yrs ensure pure breeding bull Crossed 1 variety with another
- Observed result in next generation bull Mendel examined
- Flower colour - Purple or white - Flower position - Axial or terminal - Seed shape - Round or wrinkled - Seed colour - Green or yellow - Pod shape - Inflated or constricted - Pod colour - Green or yellow - Stem height - Tall or short
2 of 9
bull Mendel needed to control fertilisation - Self fertilisation ensured - Placed bag over flowers made sure pollen from stamens lands on carpal of same flower - Cross fertilisation ensured - Cutting off stamens before pollen was produced - Dusting carpal with pollen from another plant - Increase reliability - Mendel used thousands of plants in each experiment
bull Mendel worked with true breeding plants - Self fertilising plants - Produced offspring identical to parents 1 Mendel cross fertilised 2 true breeding plants for 1 characteristic - Eg Tall plants crossed with short plants - Mendel named these parent generation (P1) 2 Offspring produced called F1 (1st filial) generation 3 F1 generation self fertilised cross fertilised to produce F2
generation bull Each of seven traits had
- Dominant factor - Recessive factor - When 2 true breeding plants crossed only DOMINANT factor appeared in F1 - Recessive factor appeared in F2 in ratio 31 - (dominant recessive) relationship
3 of 9
Describe the aspects of the experimental techniques used by Mendel that led to his success
bull Mendel was successful because - Used peas - Easily grown - Reproduced rapidly - Selected easily observable characteristics - Strictly controlled fertilisation process - Used mathematics rigorously to analyse results - Used large number of plants - Studied traits that had 2 easily identified factors - Lucky because each trait on separate chromosome - No crossing over occurred - Not sex-linked characteristics
4 of 9
Describe outcomes of monohybrid crosses involving simple dominance using Mendels explanations
bull Monohybrid crosses involve 1 factor only - Eg Cross may involve a true breeding (homozygous) tall with a true breeding (homozygous) short plant - Produces a F1 generation where all plants are tall - Mendel explained F1 generation trait as a DOMINANT factor - Mendel explained observable ratios - Parents Homozygous tall homozygous short - F1 ALL TALL - F2 3 TALL 1 SHORT - Mendalian ratio (monohybrid ratio) 31
5 of 9
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
4 of 12
Eg - Most famous transitional form is Archaeopteryx - Fossil first thought to be a therapsid reptile - Reptilian features include - Teeth - Reptilian-like skeleton - Long jointed tail - Bird like features include - Feathers - Wishbone sternum to attach flight muscles - Wings - Provides evolutionary pathway between dinosaursreptiles amp birds Eg - Lung fish - Absorb O2 from air - Appeared 400mya - End of Devonian age - Thought amphibians developed from this line - Had bones in fins - May be able to walkdrag itself on land
Biogeography
bull Study of distribution of organisms over Earth - Distribution patterns provide evidence of species originating from common ancestors when isolated become new species
bull Earth has a number of biogeographical zones - Eg Arctic zone - Each with specific enviro features - Therefore contain organisms with specific adaptive features
bull Charles Darwin Alfred Russel observed distribution of species into different biographic regions - Saw as major evidence to support theory of evolution - Argued that animals in different regions come from ancestors in that region adapted to conditions overtime
5 of 12
- Darwin suggested line (Wallacersquos Line) separate distribution of organisms of Asia amp Aust
bull Special Creation prevailing religious based explanation of the time - Didnrsquot explain why islands with similar conditions didnrsquot contain same flora amp fauna - Darwin proposed migration amp evolution much more satisfactory explanations for unique flora amp fauna in places such as Aust
Comparative Embryology
bull Study of embryos of different organisms - Looking for similarities differences - Similarities suggest common ancestry
bull Obvious similarities between embryos of fish amphibians reptiles birds mammals - Comparison of vertebrate embryos show all have gill slits even though they donrsquot remain later in life except in fish - Indicates fundamental step common to all vertebrates - Supports idea of a common ancestor
bull All chordates possess pharyngeal gill pouches at some stage in development
6 of 12
Comparative Anatomy
bull Study of similarities differences in structure between different organisms - Similar structures evidence of common ancestry
bull Anatomical structures on different organisms that have same plan but different functions called homologous structures - Homologous structures evidence for evolution - Structures shared by related species because inherited some way from a common ancestor
o Eg of homologous structure - Pentadactyl limb found in amphibians reptiles birds mammals - Basic plan consists of 1 bone in upper limb 2 in lower limb leading 5 fingerstoes - In bats limb modified to form a wing with fingers extended skin stretched between each finger - Whales have fully formed pentadactyl limb within their single paddle like fin - Limbs are modified adaptations to different enviros - Suggests animals descended from common ancestors with pentadactyl limbs
o Eg Xylem - Ferns conifers flowering plants have vascular tissue
7 of 12
Biochemistry
bull Some biochemical processes same for all living cells - Certain proteins common in a large number of organisms
bull Recent technology advances allowed comparison of organisms on molecular basis rather than structural - Previously impossible between distantly related species such as an orchid amp a mouse
bull Study of amino acid sequences shows that related species share more common sequences than unrelated species - Particular evidence derived form haemoglobin sequences showing humans amp rhesus monkey share all but 8 amino acid sequences (10) There are 125 amino acid differences between humans amp lampreys - Supports fossil embryological anatomical evidence that humans are more closely related to rhesus monkeys than lampreys
Explain how DarwinWallaces theory of evolution by natural selection and isolation accounts for adaptive radiation leading to divergent evolution and convergent evolution
bull DarwinWallace theory outlines characteristics favourable to reproduction amp survival of organisms in their environment will be selected for and over time new species will appear in response to environmental changes
bull Adaptive radiation - Refers to variety of different species evolved from ancestral lines as a result of migration amp isolation - DarwinWallace theory of natural selection amp isolation provides mechanism for adaptive radiation - If groups of a population become isolated chances are high that they will encounter differing selective pressure as each environment evolves independently - Eventually 2 populations may change enough to become 2 separate| species
8 of 12
o Eg Biodiversity of flora fauna unique to Aust result of adaptive radiation - When Aust separated from Gondwana organisms evolved due to selective pressure from changing environment - Supports DarwinWallace theory of evolution
bull Adaptive radiation can lead to divergent evolution convergent evolution
- Divergent evolution - Occurs when closely related species experience different environments - Vastly different characteristics will be selected - Overtime species evolve differently appear quite differently - Eg Elephants large animals closely related to the hyrax small guinea pig like creature - Live amongst rocky outcrops on mountains - Comparison of skeletons indicates close relationship - Convergent evolution - Occurs when relatively unrelated species develop similar structures physiology behaviours in response to similar selective pressures from similar environments - Eg Dolphins (mammals) sharks (cartilaginous fish) evolved streamlined body shape amp fins enabling efficient movement in water - Only remotely related as vertebrates - Communal social behaviour developed independently in ants bees termites
9 of 12
Plan choose equipment or resources and perform a first-hand investigation to model natural selection
bull lsquoStick birdrsquo a simple game using red amp green toothpicks - Red green toothpicks scattered over area on ground with a green background - One person in group given task of picking up as many toothpicks in given time - Count red toothpicks collected count green toothpicks collected - Repeat game on a neutral background - Collate results
bull More red toothpicks collected on green background because - Green toothpicks have physiological adaptation camouflage - Allows them to blend into background escaping predator - Natural selection has allowed green toothpicks to survive under selective pressure of predator - Red toothpicks will die out leaving green species to survive amp reproduce
bull Enviro selected better adapted lsquowormsrsquo to reproduce amp become greater in number - Green worms will become greater in number - Become prevalent phenotype within worm population
10 of 12
Analyse information from secondary sources to prepare a case study to show how an environmental change can lead changes in a species
The Kangaroo - Kangaroos offer a unique opportunity to study evolutionary changes within a group of Australian mammals - Have best known fossil record most extensively studied of all Aust mammals - Have undergone rapid evolutionary change - Commonly good indicators of restricted enviros - Middle of Miocene (10-12 million ya) - Aust became warmer - Aust moved north - Aridity (dryness) increased - Rainfall became seasonal - Forests changed - Dominated by eucalypts - Some pockets of open forests - Grassland thriving in drier conditions - Kangaroos became abundant - Evolving to take advantage of variety of new environments emerging from changes - Dominated grasslands - Increased in size - Rapidly diversified - Kangaroos of this age show hopping - 5th toe adaptation to arboreal (live in trees) life lost - Fossils show adaptations to grazing life - Pliocene (5-2 million ya) - Continent continued to dry out at faster rate - Rainforest restricted to east coastal regions - Woodlands grasslands replaced rainforests in central Aust
11 of 12
- End of Pliocene - Evolved bounding strides - Take advantage of vast grasslands in arid areas - Important adaptation - Pleistocene (16 million ya) to present - Kangaroos at most diverse - Varied from giant kangaroos to small types - Adapted to variety of enviros - Grasslands led to development of specialised teeth - Increased tempoC led to larger kangaroos
Use available evidence to Analyse using a named example how advances in technology have changed scientific thinking about evolutionary relationships
bull Technological changes - Up until 1950rsquos relationships between organisms worked out by - Anatomical similarities - Became possible to analyse protein sequence data amp DNA sequence data - Proteins (Eg Haemoglobin) compared amp similarities discovered based on biochemical similarities - Rate of change estimated - Possible to work out molecular clock - Estimates when 2 organisms shared common ancestors Eg Similarities between humans chimpanzees worked out by comparing amino acid sequences in DNA
12 of 12
Analyse information from secondary sources on the historical development of theories of evolution and use available evidence to assess social and political influences on these developments
bull 1735 - Linnaeus - Published classification system - Humans apes classified together - No idea of evolution in classification though strongly contested
bull Late 1700s - Erasmus Darwin (grandpa Darwin) - Suggested life came from single source
bull 1809 - Lamarck - 1st theory of evolution - Variation developed due to lsquousersquo amp lsquodisusersquo - Changes passed onto offspring - Theory proved incorrect - Challenged creationism - Helped Darwinrsquos ideas be recognised
bull 1859 - Darwin - Published lsquoOn the Origins of Species by Means of Natural Selection - In 1871 applied theory to humans in lsquoDescent of Manrsquo
bull Early 1900s - Scientists refined Darwinrsquos theory
bull Social political influences - Up until Darwinrsquos theory - Predominant Western view creationism - Diversity of living things created for enviro at same time by God in 6 days remain unchanged unrelated - Despite mounting evidence Darwinrsquos theory still rejected by religious groups - Darwinrsquos theory of descendants from apes caused political social outrage
1 of 9
HSC Biology Core 2 ndash Blueprint of Life
Focus 2
Gregor Mendels experiments helped advance our knowledge of the inheritance of characteristics
Outline the experiments carried out by Gregor Mendel
bull Mendel studied heredity bull 1860rsquos Gregor Mendel
- Formulated principles of genetics - Through careful methodical experimentation with garden peas - Garden peas have short reproductive cycle - Easily distinguishable characteristics - Easy to grow
bull Bred each variety for 2 yrs ensure pure breeding bull Crossed 1 variety with another
- Observed result in next generation bull Mendel examined
- Flower colour - Purple or white - Flower position - Axial or terminal - Seed shape - Round or wrinkled - Seed colour - Green or yellow - Pod shape - Inflated or constricted - Pod colour - Green or yellow - Stem height - Tall or short
2 of 9
bull Mendel needed to control fertilisation - Self fertilisation ensured - Placed bag over flowers made sure pollen from stamens lands on carpal of same flower - Cross fertilisation ensured - Cutting off stamens before pollen was produced - Dusting carpal with pollen from another plant - Increase reliability - Mendel used thousands of plants in each experiment
bull Mendel worked with true breeding plants - Self fertilising plants - Produced offspring identical to parents 1 Mendel cross fertilised 2 true breeding plants for 1 characteristic - Eg Tall plants crossed with short plants - Mendel named these parent generation (P1) 2 Offspring produced called F1 (1st filial) generation 3 F1 generation self fertilised cross fertilised to produce F2
generation bull Each of seven traits had
- Dominant factor - Recessive factor - When 2 true breeding plants crossed only DOMINANT factor appeared in F1 - Recessive factor appeared in F2 in ratio 31 - (dominant recessive) relationship
3 of 9
Describe the aspects of the experimental techniques used by Mendel that led to his success
bull Mendel was successful because - Used peas - Easily grown - Reproduced rapidly - Selected easily observable characteristics - Strictly controlled fertilisation process - Used mathematics rigorously to analyse results - Used large number of plants - Studied traits that had 2 easily identified factors - Lucky because each trait on separate chromosome - No crossing over occurred - Not sex-linked characteristics
4 of 9
Describe outcomes of monohybrid crosses involving simple dominance using Mendels explanations
bull Monohybrid crosses involve 1 factor only - Eg Cross may involve a true breeding (homozygous) tall with a true breeding (homozygous) short plant - Produces a F1 generation where all plants are tall - Mendel explained F1 generation trait as a DOMINANT factor - Mendel explained observable ratios - Parents Homozygous tall homozygous short - F1 ALL TALL - F2 3 TALL 1 SHORT - Mendalian ratio (monohybrid ratio) 31
5 of 9
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
5 of 12
- Darwin suggested line (Wallacersquos Line) separate distribution of organisms of Asia amp Aust
bull Special Creation prevailing religious based explanation of the time - Didnrsquot explain why islands with similar conditions didnrsquot contain same flora amp fauna - Darwin proposed migration amp evolution much more satisfactory explanations for unique flora amp fauna in places such as Aust
Comparative Embryology
bull Study of embryos of different organisms - Looking for similarities differences - Similarities suggest common ancestry
bull Obvious similarities between embryos of fish amphibians reptiles birds mammals - Comparison of vertebrate embryos show all have gill slits even though they donrsquot remain later in life except in fish - Indicates fundamental step common to all vertebrates - Supports idea of a common ancestor
bull All chordates possess pharyngeal gill pouches at some stage in development
6 of 12
Comparative Anatomy
bull Study of similarities differences in structure between different organisms - Similar structures evidence of common ancestry
bull Anatomical structures on different organisms that have same plan but different functions called homologous structures - Homologous structures evidence for evolution - Structures shared by related species because inherited some way from a common ancestor
o Eg of homologous structure - Pentadactyl limb found in amphibians reptiles birds mammals - Basic plan consists of 1 bone in upper limb 2 in lower limb leading 5 fingerstoes - In bats limb modified to form a wing with fingers extended skin stretched between each finger - Whales have fully formed pentadactyl limb within their single paddle like fin - Limbs are modified adaptations to different enviros - Suggests animals descended from common ancestors with pentadactyl limbs
o Eg Xylem - Ferns conifers flowering plants have vascular tissue
7 of 12
Biochemistry
bull Some biochemical processes same for all living cells - Certain proteins common in a large number of organisms
bull Recent technology advances allowed comparison of organisms on molecular basis rather than structural - Previously impossible between distantly related species such as an orchid amp a mouse
bull Study of amino acid sequences shows that related species share more common sequences than unrelated species - Particular evidence derived form haemoglobin sequences showing humans amp rhesus monkey share all but 8 amino acid sequences (10) There are 125 amino acid differences between humans amp lampreys - Supports fossil embryological anatomical evidence that humans are more closely related to rhesus monkeys than lampreys
Explain how DarwinWallaces theory of evolution by natural selection and isolation accounts for adaptive radiation leading to divergent evolution and convergent evolution
bull DarwinWallace theory outlines characteristics favourable to reproduction amp survival of organisms in their environment will be selected for and over time new species will appear in response to environmental changes
bull Adaptive radiation - Refers to variety of different species evolved from ancestral lines as a result of migration amp isolation - DarwinWallace theory of natural selection amp isolation provides mechanism for adaptive radiation - If groups of a population become isolated chances are high that they will encounter differing selective pressure as each environment evolves independently - Eventually 2 populations may change enough to become 2 separate| species
8 of 12
o Eg Biodiversity of flora fauna unique to Aust result of adaptive radiation - When Aust separated from Gondwana organisms evolved due to selective pressure from changing environment - Supports DarwinWallace theory of evolution
bull Adaptive radiation can lead to divergent evolution convergent evolution
- Divergent evolution - Occurs when closely related species experience different environments - Vastly different characteristics will be selected - Overtime species evolve differently appear quite differently - Eg Elephants large animals closely related to the hyrax small guinea pig like creature - Live amongst rocky outcrops on mountains - Comparison of skeletons indicates close relationship - Convergent evolution - Occurs when relatively unrelated species develop similar structures physiology behaviours in response to similar selective pressures from similar environments - Eg Dolphins (mammals) sharks (cartilaginous fish) evolved streamlined body shape amp fins enabling efficient movement in water - Only remotely related as vertebrates - Communal social behaviour developed independently in ants bees termites
9 of 12
Plan choose equipment or resources and perform a first-hand investigation to model natural selection
bull lsquoStick birdrsquo a simple game using red amp green toothpicks - Red green toothpicks scattered over area on ground with a green background - One person in group given task of picking up as many toothpicks in given time - Count red toothpicks collected count green toothpicks collected - Repeat game on a neutral background - Collate results
bull More red toothpicks collected on green background because - Green toothpicks have physiological adaptation camouflage - Allows them to blend into background escaping predator - Natural selection has allowed green toothpicks to survive under selective pressure of predator - Red toothpicks will die out leaving green species to survive amp reproduce
bull Enviro selected better adapted lsquowormsrsquo to reproduce amp become greater in number - Green worms will become greater in number - Become prevalent phenotype within worm population
10 of 12
Analyse information from secondary sources to prepare a case study to show how an environmental change can lead changes in a species
The Kangaroo - Kangaroos offer a unique opportunity to study evolutionary changes within a group of Australian mammals - Have best known fossil record most extensively studied of all Aust mammals - Have undergone rapid evolutionary change - Commonly good indicators of restricted enviros - Middle of Miocene (10-12 million ya) - Aust became warmer - Aust moved north - Aridity (dryness) increased - Rainfall became seasonal - Forests changed - Dominated by eucalypts - Some pockets of open forests - Grassland thriving in drier conditions - Kangaroos became abundant - Evolving to take advantage of variety of new environments emerging from changes - Dominated grasslands - Increased in size - Rapidly diversified - Kangaroos of this age show hopping - 5th toe adaptation to arboreal (live in trees) life lost - Fossils show adaptations to grazing life - Pliocene (5-2 million ya) - Continent continued to dry out at faster rate - Rainforest restricted to east coastal regions - Woodlands grasslands replaced rainforests in central Aust
11 of 12
- End of Pliocene - Evolved bounding strides - Take advantage of vast grasslands in arid areas - Important adaptation - Pleistocene (16 million ya) to present - Kangaroos at most diverse - Varied from giant kangaroos to small types - Adapted to variety of enviros - Grasslands led to development of specialised teeth - Increased tempoC led to larger kangaroos
Use available evidence to Analyse using a named example how advances in technology have changed scientific thinking about evolutionary relationships
bull Technological changes - Up until 1950rsquos relationships between organisms worked out by - Anatomical similarities - Became possible to analyse protein sequence data amp DNA sequence data - Proteins (Eg Haemoglobin) compared amp similarities discovered based on biochemical similarities - Rate of change estimated - Possible to work out molecular clock - Estimates when 2 organisms shared common ancestors Eg Similarities between humans chimpanzees worked out by comparing amino acid sequences in DNA
12 of 12
Analyse information from secondary sources on the historical development of theories of evolution and use available evidence to assess social and political influences on these developments
bull 1735 - Linnaeus - Published classification system - Humans apes classified together - No idea of evolution in classification though strongly contested
bull Late 1700s - Erasmus Darwin (grandpa Darwin) - Suggested life came from single source
bull 1809 - Lamarck - 1st theory of evolution - Variation developed due to lsquousersquo amp lsquodisusersquo - Changes passed onto offspring - Theory proved incorrect - Challenged creationism - Helped Darwinrsquos ideas be recognised
bull 1859 - Darwin - Published lsquoOn the Origins of Species by Means of Natural Selection - In 1871 applied theory to humans in lsquoDescent of Manrsquo
bull Early 1900s - Scientists refined Darwinrsquos theory
bull Social political influences - Up until Darwinrsquos theory - Predominant Western view creationism - Diversity of living things created for enviro at same time by God in 6 days remain unchanged unrelated - Despite mounting evidence Darwinrsquos theory still rejected by religious groups - Darwinrsquos theory of descendants from apes caused political social outrage
1 of 9
HSC Biology Core 2 ndash Blueprint of Life
Focus 2
Gregor Mendels experiments helped advance our knowledge of the inheritance of characteristics
Outline the experiments carried out by Gregor Mendel
bull Mendel studied heredity bull 1860rsquos Gregor Mendel
- Formulated principles of genetics - Through careful methodical experimentation with garden peas - Garden peas have short reproductive cycle - Easily distinguishable characteristics - Easy to grow
bull Bred each variety for 2 yrs ensure pure breeding bull Crossed 1 variety with another
- Observed result in next generation bull Mendel examined
- Flower colour - Purple or white - Flower position - Axial or terminal - Seed shape - Round or wrinkled - Seed colour - Green or yellow - Pod shape - Inflated or constricted - Pod colour - Green or yellow - Stem height - Tall or short
2 of 9
bull Mendel needed to control fertilisation - Self fertilisation ensured - Placed bag over flowers made sure pollen from stamens lands on carpal of same flower - Cross fertilisation ensured - Cutting off stamens before pollen was produced - Dusting carpal with pollen from another plant - Increase reliability - Mendel used thousands of plants in each experiment
bull Mendel worked with true breeding plants - Self fertilising plants - Produced offspring identical to parents 1 Mendel cross fertilised 2 true breeding plants for 1 characteristic - Eg Tall plants crossed with short plants - Mendel named these parent generation (P1) 2 Offspring produced called F1 (1st filial) generation 3 F1 generation self fertilised cross fertilised to produce F2
generation bull Each of seven traits had
- Dominant factor - Recessive factor - When 2 true breeding plants crossed only DOMINANT factor appeared in F1 - Recessive factor appeared in F2 in ratio 31 - (dominant recessive) relationship
3 of 9
Describe the aspects of the experimental techniques used by Mendel that led to his success
bull Mendel was successful because - Used peas - Easily grown - Reproduced rapidly - Selected easily observable characteristics - Strictly controlled fertilisation process - Used mathematics rigorously to analyse results - Used large number of plants - Studied traits that had 2 easily identified factors - Lucky because each trait on separate chromosome - No crossing over occurred - Not sex-linked characteristics
4 of 9
Describe outcomes of monohybrid crosses involving simple dominance using Mendels explanations
bull Monohybrid crosses involve 1 factor only - Eg Cross may involve a true breeding (homozygous) tall with a true breeding (homozygous) short plant - Produces a F1 generation where all plants are tall - Mendel explained F1 generation trait as a DOMINANT factor - Mendel explained observable ratios - Parents Homozygous tall homozygous short - F1 ALL TALL - F2 3 TALL 1 SHORT - Mendalian ratio (monohybrid ratio) 31
5 of 9
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
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XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
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- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
6 of 12
Comparative Anatomy
bull Study of similarities differences in structure between different organisms - Similar structures evidence of common ancestry
bull Anatomical structures on different organisms that have same plan but different functions called homologous structures - Homologous structures evidence for evolution - Structures shared by related species because inherited some way from a common ancestor
o Eg of homologous structure - Pentadactyl limb found in amphibians reptiles birds mammals - Basic plan consists of 1 bone in upper limb 2 in lower limb leading 5 fingerstoes - In bats limb modified to form a wing with fingers extended skin stretched between each finger - Whales have fully formed pentadactyl limb within their single paddle like fin - Limbs are modified adaptations to different enviros - Suggests animals descended from common ancestors with pentadactyl limbs
o Eg Xylem - Ferns conifers flowering plants have vascular tissue
7 of 12
Biochemistry
bull Some biochemical processes same for all living cells - Certain proteins common in a large number of organisms
bull Recent technology advances allowed comparison of organisms on molecular basis rather than structural - Previously impossible between distantly related species such as an orchid amp a mouse
bull Study of amino acid sequences shows that related species share more common sequences than unrelated species - Particular evidence derived form haemoglobin sequences showing humans amp rhesus monkey share all but 8 amino acid sequences (10) There are 125 amino acid differences between humans amp lampreys - Supports fossil embryological anatomical evidence that humans are more closely related to rhesus monkeys than lampreys
Explain how DarwinWallaces theory of evolution by natural selection and isolation accounts for adaptive radiation leading to divergent evolution and convergent evolution
bull DarwinWallace theory outlines characteristics favourable to reproduction amp survival of organisms in their environment will be selected for and over time new species will appear in response to environmental changes
bull Adaptive radiation - Refers to variety of different species evolved from ancestral lines as a result of migration amp isolation - DarwinWallace theory of natural selection amp isolation provides mechanism for adaptive radiation - If groups of a population become isolated chances are high that they will encounter differing selective pressure as each environment evolves independently - Eventually 2 populations may change enough to become 2 separate| species
8 of 12
o Eg Biodiversity of flora fauna unique to Aust result of adaptive radiation - When Aust separated from Gondwana organisms evolved due to selective pressure from changing environment - Supports DarwinWallace theory of evolution
bull Adaptive radiation can lead to divergent evolution convergent evolution
- Divergent evolution - Occurs when closely related species experience different environments - Vastly different characteristics will be selected - Overtime species evolve differently appear quite differently - Eg Elephants large animals closely related to the hyrax small guinea pig like creature - Live amongst rocky outcrops on mountains - Comparison of skeletons indicates close relationship - Convergent evolution - Occurs when relatively unrelated species develop similar structures physiology behaviours in response to similar selective pressures from similar environments - Eg Dolphins (mammals) sharks (cartilaginous fish) evolved streamlined body shape amp fins enabling efficient movement in water - Only remotely related as vertebrates - Communal social behaviour developed independently in ants bees termites
9 of 12
Plan choose equipment or resources and perform a first-hand investigation to model natural selection
bull lsquoStick birdrsquo a simple game using red amp green toothpicks - Red green toothpicks scattered over area on ground with a green background - One person in group given task of picking up as many toothpicks in given time - Count red toothpicks collected count green toothpicks collected - Repeat game on a neutral background - Collate results
bull More red toothpicks collected on green background because - Green toothpicks have physiological adaptation camouflage - Allows them to blend into background escaping predator - Natural selection has allowed green toothpicks to survive under selective pressure of predator - Red toothpicks will die out leaving green species to survive amp reproduce
bull Enviro selected better adapted lsquowormsrsquo to reproduce amp become greater in number - Green worms will become greater in number - Become prevalent phenotype within worm population
10 of 12
Analyse information from secondary sources to prepare a case study to show how an environmental change can lead changes in a species
The Kangaroo - Kangaroos offer a unique opportunity to study evolutionary changes within a group of Australian mammals - Have best known fossil record most extensively studied of all Aust mammals - Have undergone rapid evolutionary change - Commonly good indicators of restricted enviros - Middle of Miocene (10-12 million ya) - Aust became warmer - Aust moved north - Aridity (dryness) increased - Rainfall became seasonal - Forests changed - Dominated by eucalypts - Some pockets of open forests - Grassland thriving in drier conditions - Kangaroos became abundant - Evolving to take advantage of variety of new environments emerging from changes - Dominated grasslands - Increased in size - Rapidly diversified - Kangaroos of this age show hopping - 5th toe adaptation to arboreal (live in trees) life lost - Fossils show adaptations to grazing life - Pliocene (5-2 million ya) - Continent continued to dry out at faster rate - Rainforest restricted to east coastal regions - Woodlands grasslands replaced rainforests in central Aust
11 of 12
- End of Pliocene - Evolved bounding strides - Take advantage of vast grasslands in arid areas - Important adaptation - Pleistocene (16 million ya) to present - Kangaroos at most diverse - Varied from giant kangaroos to small types - Adapted to variety of enviros - Grasslands led to development of specialised teeth - Increased tempoC led to larger kangaroos
Use available evidence to Analyse using a named example how advances in technology have changed scientific thinking about evolutionary relationships
bull Technological changes - Up until 1950rsquos relationships between organisms worked out by - Anatomical similarities - Became possible to analyse protein sequence data amp DNA sequence data - Proteins (Eg Haemoglobin) compared amp similarities discovered based on biochemical similarities - Rate of change estimated - Possible to work out molecular clock - Estimates when 2 organisms shared common ancestors Eg Similarities between humans chimpanzees worked out by comparing amino acid sequences in DNA
12 of 12
Analyse information from secondary sources on the historical development of theories of evolution and use available evidence to assess social and political influences on these developments
bull 1735 - Linnaeus - Published classification system - Humans apes classified together - No idea of evolution in classification though strongly contested
bull Late 1700s - Erasmus Darwin (grandpa Darwin) - Suggested life came from single source
bull 1809 - Lamarck - 1st theory of evolution - Variation developed due to lsquousersquo amp lsquodisusersquo - Changes passed onto offspring - Theory proved incorrect - Challenged creationism - Helped Darwinrsquos ideas be recognised
bull 1859 - Darwin - Published lsquoOn the Origins of Species by Means of Natural Selection - In 1871 applied theory to humans in lsquoDescent of Manrsquo
bull Early 1900s - Scientists refined Darwinrsquos theory
bull Social political influences - Up until Darwinrsquos theory - Predominant Western view creationism - Diversity of living things created for enviro at same time by God in 6 days remain unchanged unrelated - Despite mounting evidence Darwinrsquos theory still rejected by religious groups - Darwinrsquos theory of descendants from apes caused political social outrage
1 of 9
HSC Biology Core 2 ndash Blueprint of Life
Focus 2
Gregor Mendels experiments helped advance our knowledge of the inheritance of characteristics
Outline the experiments carried out by Gregor Mendel
bull Mendel studied heredity bull 1860rsquos Gregor Mendel
- Formulated principles of genetics - Through careful methodical experimentation with garden peas - Garden peas have short reproductive cycle - Easily distinguishable characteristics - Easy to grow
bull Bred each variety for 2 yrs ensure pure breeding bull Crossed 1 variety with another
- Observed result in next generation bull Mendel examined
- Flower colour - Purple or white - Flower position - Axial or terminal - Seed shape - Round or wrinkled - Seed colour - Green or yellow - Pod shape - Inflated or constricted - Pod colour - Green or yellow - Stem height - Tall or short
2 of 9
bull Mendel needed to control fertilisation - Self fertilisation ensured - Placed bag over flowers made sure pollen from stamens lands on carpal of same flower - Cross fertilisation ensured - Cutting off stamens before pollen was produced - Dusting carpal with pollen from another plant - Increase reliability - Mendel used thousands of plants in each experiment
bull Mendel worked with true breeding plants - Self fertilising plants - Produced offspring identical to parents 1 Mendel cross fertilised 2 true breeding plants for 1 characteristic - Eg Tall plants crossed with short plants - Mendel named these parent generation (P1) 2 Offspring produced called F1 (1st filial) generation 3 F1 generation self fertilised cross fertilised to produce F2
generation bull Each of seven traits had
- Dominant factor - Recessive factor - When 2 true breeding plants crossed only DOMINANT factor appeared in F1 - Recessive factor appeared in F2 in ratio 31 - (dominant recessive) relationship
3 of 9
Describe the aspects of the experimental techniques used by Mendel that led to his success
bull Mendel was successful because - Used peas - Easily grown - Reproduced rapidly - Selected easily observable characteristics - Strictly controlled fertilisation process - Used mathematics rigorously to analyse results - Used large number of plants - Studied traits that had 2 easily identified factors - Lucky because each trait on separate chromosome - No crossing over occurred - Not sex-linked characteristics
4 of 9
Describe outcomes of monohybrid crosses involving simple dominance using Mendels explanations
bull Monohybrid crosses involve 1 factor only - Eg Cross may involve a true breeding (homozygous) tall with a true breeding (homozygous) short plant - Produces a F1 generation where all plants are tall - Mendel explained F1 generation trait as a DOMINANT factor - Mendel explained observable ratios - Parents Homozygous tall homozygous short - F1 ALL TALL - F2 3 TALL 1 SHORT - Mendalian ratio (monohybrid ratio) 31
5 of 9
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
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- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
7 of 12
Biochemistry
bull Some biochemical processes same for all living cells - Certain proteins common in a large number of organisms
bull Recent technology advances allowed comparison of organisms on molecular basis rather than structural - Previously impossible between distantly related species such as an orchid amp a mouse
bull Study of amino acid sequences shows that related species share more common sequences than unrelated species - Particular evidence derived form haemoglobin sequences showing humans amp rhesus monkey share all but 8 amino acid sequences (10) There are 125 amino acid differences between humans amp lampreys - Supports fossil embryological anatomical evidence that humans are more closely related to rhesus monkeys than lampreys
Explain how DarwinWallaces theory of evolution by natural selection and isolation accounts for adaptive radiation leading to divergent evolution and convergent evolution
bull DarwinWallace theory outlines characteristics favourable to reproduction amp survival of organisms in their environment will be selected for and over time new species will appear in response to environmental changes
bull Adaptive radiation - Refers to variety of different species evolved from ancestral lines as a result of migration amp isolation - DarwinWallace theory of natural selection amp isolation provides mechanism for adaptive radiation - If groups of a population become isolated chances are high that they will encounter differing selective pressure as each environment evolves independently - Eventually 2 populations may change enough to become 2 separate| species
8 of 12
o Eg Biodiversity of flora fauna unique to Aust result of adaptive radiation - When Aust separated from Gondwana organisms evolved due to selective pressure from changing environment - Supports DarwinWallace theory of evolution
bull Adaptive radiation can lead to divergent evolution convergent evolution
- Divergent evolution - Occurs when closely related species experience different environments - Vastly different characteristics will be selected - Overtime species evolve differently appear quite differently - Eg Elephants large animals closely related to the hyrax small guinea pig like creature - Live amongst rocky outcrops on mountains - Comparison of skeletons indicates close relationship - Convergent evolution - Occurs when relatively unrelated species develop similar structures physiology behaviours in response to similar selective pressures from similar environments - Eg Dolphins (mammals) sharks (cartilaginous fish) evolved streamlined body shape amp fins enabling efficient movement in water - Only remotely related as vertebrates - Communal social behaviour developed independently in ants bees termites
9 of 12
Plan choose equipment or resources and perform a first-hand investigation to model natural selection
bull lsquoStick birdrsquo a simple game using red amp green toothpicks - Red green toothpicks scattered over area on ground with a green background - One person in group given task of picking up as many toothpicks in given time - Count red toothpicks collected count green toothpicks collected - Repeat game on a neutral background - Collate results
bull More red toothpicks collected on green background because - Green toothpicks have physiological adaptation camouflage - Allows them to blend into background escaping predator - Natural selection has allowed green toothpicks to survive under selective pressure of predator - Red toothpicks will die out leaving green species to survive amp reproduce
bull Enviro selected better adapted lsquowormsrsquo to reproduce amp become greater in number - Green worms will become greater in number - Become prevalent phenotype within worm population
10 of 12
Analyse information from secondary sources to prepare a case study to show how an environmental change can lead changes in a species
The Kangaroo - Kangaroos offer a unique opportunity to study evolutionary changes within a group of Australian mammals - Have best known fossil record most extensively studied of all Aust mammals - Have undergone rapid evolutionary change - Commonly good indicators of restricted enviros - Middle of Miocene (10-12 million ya) - Aust became warmer - Aust moved north - Aridity (dryness) increased - Rainfall became seasonal - Forests changed - Dominated by eucalypts - Some pockets of open forests - Grassland thriving in drier conditions - Kangaroos became abundant - Evolving to take advantage of variety of new environments emerging from changes - Dominated grasslands - Increased in size - Rapidly diversified - Kangaroos of this age show hopping - 5th toe adaptation to arboreal (live in trees) life lost - Fossils show adaptations to grazing life - Pliocene (5-2 million ya) - Continent continued to dry out at faster rate - Rainforest restricted to east coastal regions - Woodlands grasslands replaced rainforests in central Aust
11 of 12
- End of Pliocene - Evolved bounding strides - Take advantage of vast grasslands in arid areas - Important adaptation - Pleistocene (16 million ya) to present - Kangaroos at most diverse - Varied from giant kangaroos to small types - Adapted to variety of enviros - Grasslands led to development of specialised teeth - Increased tempoC led to larger kangaroos
Use available evidence to Analyse using a named example how advances in technology have changed scientific thinking about evolutionary relationships
bull Technological changes - Up until 1950rsquos relationships between organisms worked out by - Anatomical similarities - Became possible to analyse protein sequence data amp DNA sequence data - Proteins (Eg Haemoglobin) compared amp similarities discovered based on biochemical similarities - Rate of change estimated - Possible to work out molecular clock - Estimates when 2 organisms shared common ancestors Eg Similarities between humans chimpanzees worked out by comparing amino acid sequences in DNA
12 of 12
Analyse information from secondary sources on the historical development of theories of evolution and use available evidence to assess social and political influences on these developments
bull 1735 - Linnaeus - Published classification system - Humans apes classified together - No idea of evolution in classification though strongly contested
bull Late 1700s - Erasmus Darwin (grandpa Darwin) - Suggested life came from single source
bull 1809 - Lamarck - 1st theory of evolution - Variation developed due to lsquousersquo amp lsquodisusersquo - Changes passed onto offspring - Theory proved incorrect - Challenged creationism - Helped Darwinrsquos ideas be recognised
bull 1859 - Darwin - Published lsquoOn the Origins of Species by Means of Natural Selection - In 1871 applied theory to humans in lsquoDescent of Manrsquo
bull Early 1900s - Scientists refined Darwinrsquos theory
bull Social political influences - Up until Darwinrsquos theory - Predominant Western view creationism - Diversity of living things created for enviro at same time by God in 6 days remain unchanged unrelated - Despite mounting evidence Darwinrsquos theory still rejected by religious groups - Darwinrsquos theory of descendants from apes caused political social outrage
1 of 9
HSC Biology Core 2 ndash Blueprint of Life
Focus 2
Gregor Mendels experiments helped advance our knowledge of the inheritance of characteristics
Outline the experiments carried out by Gregor Mendel
bull Mendel studied heredity bull 1860rsquos Gregor Mendel
- Formulated principles of genetics - Through careful methodical experimentation with garden peas - Garden peas have short reproductive cycle - Easily distinguishable characteristics - Easy to grow
bull Bred each variety for 2 yrs ensure pure breeding bull Crossed 1 variety with another
- Observed result in next generation bull Mendel examined
- Flower colour - Purple or white - Flower position - Axial or terminal - Seed shape - Round or wrinkled - Seed colour - Green or yellow - Pod shape - Inflated or constricted - Pod colour - Green or yellow - Stem height - Tall or short
2 of 9
bull Mendel needed to control fertilisation - Self fertilisation ensured - Placed bag over flowers made sure pollen from stamens lands on carpal of same flower - Cross fertilisation ensured - Cutting off stamens before pollen was produced - Dusting carpal with pollen from another plant - Increase reliability - Mendel used thousands of plants in each experiment
bull Mendel worked with true breeding plants - Self fertilising plants - Produced offspring identical to parents 1 Mendel cross fertilised 2 true breeding plants for 1 characteristic - Eg Tall plants crossed with short plants - Mendel named these parent generation (P1) 2 Offspring produced called F1 (1st filial) generation 3 F1 generation self fertilised cross fertilised to produce F2
generation bull Each of seven traits had
- Dominant factor - Recessive factor - When 2 true breeding plants crossed only DOMINANT factor appeared in F1 - Recessive factor appeared in F2 in ratio 31 - (dominant recessive) relationship
3 of 9
Describe the aspects of the experimental techniques used by Mendel that led to his success
bull Mendel was successful because - Used peas - Easily grown - Reproduced rapidly - Selected easily observable characteristics - Strictly controlled fertilisation process - Used mathematics rigorously to analyse results - Used large number of plants - Studied traits that had 2 easily identified factors - Lucky because each trait on separate chromosome - No crossing over occurred - Not sex-linked characteristics
4 of 9
Describe outcomes of monohybrid crosses involving simple dominance using Mendels explanations
bull Monohybrid crosses involve 1 factor only - Eg Cross may involve a true breeding (homozygous) tall with a true breeding (homozygous) short plant - Produces a F1 generation where all plants are tall - Mendel explained F1 generation trait as a DOMINANT factor - Mendel explained observable ratios - Parents Homozygous tall homozygous short - F1 ALL TALL - F2 3 TALL 1 SHORT - Mendalian ratio (monohybrid ratio) 31
5 of 9
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
8 of 12
o Eg Biodiversity of flora fauna unique to Aust result of adaptive radiation - When Aust separated from Gondwana organisms evolved due to selective pressure from changing environment - Supports DarwinWallace theory of evolution
bull Adaptive radiation can lead to divergent evolution convergent evolution
- Divergent evolution - Occurs when closely related species experience different environments - Vastly different characteristics will be selected - Overtime species evolve differently appear quite differently - Eg Elephants large animals closely related to the hyrax small guinea pig like creature - Live amongst rocky outcrops on mountains - Comparison of skeletons indicates close relationship - Convergent evolution - Occurs when relatively unrelated species develop similar structures physiology behaviours in response to similar selective pressures from similar environments - Eg Dolphins (mammals) sharks (cartilaginous fish) evolved streamlined body shape amp fins enabling efficient movement in water - Only remotely related as vertebrates - Communal social behaviour developed independently in ants bees termites
9 of 12
Plan choose equipment or resources and perform a first-hand investigation to model natural selection
bull lsquoStick birdrsquo a simple game using red amp green toothpicks - Red green toothpicks scattered over area on ground with a green background - One person in group given task of picking up as many toothpicks in given time - Count red toothpicks collected count green toothpicks collected - Repeat game on a neutral background - Collate results
bull More red toothpicks collected on green background because - Green toothpicks have physiological adaptation camouflage - Allows them to blend into background escaping predator - Natural selection has allowed green toothpicks to survive under selective pressure of predator - Red toothpicks will die out leaving green species to survive amp reproduce
bull Enviro selected better adapted lsquowormsrsquo to reproduce amp become greater in number - Green worms will become greater in number - Become prevalent phenotype within worm population
10 of 12
Analyse information from secondary sources to prepare a case study to show how an environmental change can lead changes in a species
The Kangaroo - Kangaroos offer a unique opportunity to study evolutionary changes within a group of Australian mammals - Have best known fossil record most extensively studied of all Aust mammals - Have undergone rapid evolutionary change - Commonly good indicators of restricted enviros - Middle of Miocene (10-12 million ya) - Aust became warmer - Aust moved north - Aridity (dryness) increased - Rainfall became seasonal - Forests changed - Dominated by eucalypts - Some pockets of open forests - Grassland thriving in drier conditions - Kangaroos became abundant - Evolving to take advantage of variety of new environments emerging from changes - Dominated grasslands - Increased in size - Rapidly diversified - Kangaroos of this age show hopping - 5th toe adaptation to arboreal (live in trees) life lost - Fossils show adaptations to grazing life - Pliocene (5-2 million ya) - Continent continued to dry out at faster rate - Rainforest restricted to east coastal regions - Woodlands grasslands replaced rainforests in central Aust
11 of 12
- End of Pliocene - Evolved bounding strides - Take advantage of vast grasslands in arid areas - Important adaptation - Pleistocene (16 million ya) to present - Kangaroos at most diverse - Varied from giant kangaroos to small types - Adapted to variety of enviros - Grasslands led to development of specialised teeth - Increased tempoC led to larger kangaroos
Use available evidence to Analyse using a named example how advances in technology have changed scientific thinking about evolutionary relationships
bull Technological changes - Up until 1950rsquos relationships between organisms worked out by - Anatomical similarities - Became possible to analyse protein sequence data amp DNA sequence data - Proteins (Eg Haemoglobin) compared amp similarities discovered based on biochemical similarities - Rate of change estimated - Possible to work out molecular clock - Estimates when 2 organisms shared common ancestors Eg Similarities between humans chimpanzees worked out by comparing amino acid sequences in DNA
12 of 12
Analyse information from secondary sources on the historical development of theories of evolution and use available evidence to assess social and political influences on these developments
bull 1735 - Linnaeus - Published classification system - Humans apes classified together - No idea of evolution in classification though strongly contested
bull Late 1700s - Erasmus Darwin (grandpa Darwin) - Suggested life came from single source
bull 1809 - Lamarck - 1st theory of evolution - Variation developed due to lsquousersquo amp lsquodisusersquo - Changes passed onto offspring - Theory proved incorrect - Challenged creationism - Helped Darwinrsquos ideas be recognised
bull 1859 - Darwin - Published lsquoOn the Origins of Species by Means of Natural Selection - In 1871 applied theory to humans in lsquoDescent of Manrsquo
bull Early 1900s - Scientists refined Darwinrsquos theory
bull Social political influences - Up until Darwinrsquos theory - Predominant Western view creationism - Diversity of living things created for enviro at same time by God in 6 days remain unchanged unrelated - Despite mounting evidence Darwinrsquos theory still rejected by religious groups - Darwinrsquos theory of descendants from apes caused political social outrage
1 of 9
HSC Biology Core 2 ndash Blueprint of Life
Focus 2
Gregor Mendels experiments helped advance our knowledge of the inheritance of characteristics
Outline the experiments carried out by Gregor Mendel
bull Mendel studied heredity bull 1860rsquos Gregor Mendel
- Formulated principles of genetics - Through careful methodical experimentation with garden peas - Garden peas have short reproductive cycle - Easily distinguishable characteristics - Easy to grow
bull Bred each variety for 2 yrs ensure pure breeding bull Crossed 1 variety with another
- Observed result in next generation bull Mendel examined
- Flower colour - Purple or white - Flower position - Axial or terminal - Seed shape - Round or wrinkled - Seed colour - Green or yellow - Pod shape - Inflated or constricted - Pod colour - Green or yellow - Stem height - Tall or short
2 of 9
bull Mendel needed to control fertilisation - Self fertilisation ensured - Placed bag over flowers made sure pollen from stamens lands on carpal of same flower - Cross fertilisation ensured - Cutting off stamens before pollen was produced - Dusting carpal with pollen from another plant - Increase reliability - Mendel used thousands of plants in each experiment
bull Mendel worked with true breeding plants - Self fertilising plants - Produced offspring identical to parents 1 Mendel cross fertilised 2 true breeding plants for 1 characteristic - Eg Tall plants crossed with short plants - Mendel named these parent generation (P1) 2 Offspring produced called F1 (1st filial) generation 3 F1 generation self fertilised cross fertilised to produce F2
generation bull Each of seven traits had
- Dominant factor - Recessive factor - When 2 true breeding plants crossed only DOMINANT factor appeared in F1 - Recessive factor appeared in F2 in ratio 31 - (dominant recessive) relationship
3 of 9
Describe the aspects of the experimental techniques used by Mendel that led to his success
bull Mendel was successful because - Used peas - Easily grown - Reproduced rapidly - Selected easily observable characteristics - Strictly controlled fertilisation process - Used mathematics rigorously to analyse results - Used large number of plants - Studied traits that had 2 easily identified factors - Lucky because each trait on separate chromosome - No crossing over occurred - Not sex-linked characteristics
4 of 9
Describe outcomes of monohybrid crosses involving simple dominance using Mendels explanations
bull Monohybrid crosses involve 1 factor only - Eg Cross may involve a true breeding (homozygous) tall with a true breeding (homozygous) short plant - Produces a F1 generation where all plants are tall - Mendel explained F1 generation trait as a DOMINANT factor - Mendel explained observable ratios - Parents Homozygous tall homozygous short - F1 ALL TALL - F2 3 TALL 1 SHORT - Mendalian ratio (monohybrid ratio) 31
5 of 9
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
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- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
9 of 12
Plan choose equipment or resources and perform a first-hand investigation to model natural selection
bull lsquoStick birdrsquo a simple game using red amp green toothpicks - Red green toothpicks scattered over area on ground with a green background - One person in group given task of picking up as many toothpicks in given time - Count red toothpicks collected count green toothpicks collected - Repeat game on a neutral background - Collate results
bull More red toothpicks collected on green background because - Green toothpicks have physiological adaptation camouflage - Allows them to blend into background escaping predator - Natural selection has allowed green toothpicks to survive under selective pressure of predator - Red toothpicks will die out leaving green species to survive amp reproduce
bull Enviro selected better adapted lsquowormsrsquo to reproduce amp become greater in number - Green worms will become greater in number - Become prevalent phenotype within worm population
10 of 12
Analyse information from secondary sources to prepare a case study to show how an environmental change can lead changes in a species
The Kangaroo - Kangaroos offer a unique opportunity to study evolutionary changes within a group of Australian mammals - Have best known fossil record most extensively studied of all Aust mammals - Have undergone rapid evolutionary change - Commonly good indicators of restricted enviros - Middle of Miocene (10-12 million ya) - Aust became warmer - Aust moved north - Aridity (dryness) increased - Rainfall became seasonal - Forests changed - Dominated by eucalypts - Some pockets of open forests - Grassland thriving in drier conditions - Kangaroos became abundant - Evolving to take advantage of variety of new environments emerging from changes - Dominated grasslands - Increased in size - Rapidly diversified - Kangaroos of this age show hopping - 5th toe adaptation to arboreal (live in trees) life lost - Fossils show adaptations to grazing life - Pliocene (5-2 million ya) - Continent continued to dry out at faster rate - Rainforest restricted to east coastal regions - Woodlands grasslands replaced rainforests in central Aust
11 of 12
- End of Pliocene - Evolved bounding strides - Take advantage of vast grasslands in arid areas - Important adaptation - Pleistocene (16 million ya) to present - Kangaroos at most diverse - Varied from giant kangaroos to small types - Adapted to variety of enviros - Grasslands led to development of specialised teeth - Increased tempoC led to larger kangaroos
Use available evidence to Analyse using a named example how advances in technology have changed scientific thinking about evolutionary relationships
bull Technological changes - Up until 1950rsquos relationships between organisms worked out by - Anatomical similarities - Became possible to analyse protein sequence data amp DNA sequence data - Proteins (Eg Haemoglobin) compared amp similarities discovered based on biochemical similarities - Rate of change estimated - Possible to work out molecular clock - Estimates when 2 organisms shared common ancestors Eg Similarities between humans chimpanzees worked out by comparing amino acid sequences in DNA
12 of 12
Analyse information from secondary sources on the historical development of theories of evolution and use available evidence to assess social and political influences on these developments
bull 1735 - Linnaeus - Published classification system - Humans apes classified together - No idea of evolution in classification though strongly contested
bull Late 1700s - Erasmus Darwin (grandpa Darwin) - Suggested life came from single source
bull 1809 - Lamarck - 1st theory of evolution - Variation developed due to lsquousersquo amp lsquodisusersquo - Changes passed onto offspring - Theory proved incorrect - Challenged creationism - Helped Darwinrsquos ideas be recognised
bull 1859 - Darwin - Published lsquoOn the Origins of Species by Means of Natural Selection - In 1871 applied theory to humans in lsquoDescent of Manrsquo
bull Early 1900s - Scientists refined Darwinrsquos theory
bull Social political influences - Up until Darwinrsquos theory - Predominant Western view creationism - Diversity of living things created for enviro at same time by God in 6 days remain unchanged unrelated - Despite mounting evidence Darwinrsquos theory still rejected by religious groups - Darwinrsquos theory of descendants from apes caused political social outrage
1 of 9
HSC Biology Core 2 ndash Blueprint of Life
Focus 2
Gregor Mendels experiments helped advance our knowledge of the inheritance of characteristics
Outline the experiments carried out by Gregor Mendel
bull Mendel studied heredity bull 1860rsquos Gregor Mendel
- Formulated principles of genetics - Through careful methodical experimentation with garden peas - Garden peas have short reproductive cycle - Easily distinguishable characteristics - Easy to grow
bull Bred each variety for 2 yrs ensure pure breeding bull Crossed 1 variety with another
- Observed result in next generation bull Mendel examined
- Flower colour - Purple or white - Flower position - Axial or terminal - Seed shape - Round or wrinkled - Seed colour - Green or yellow - Pod shape - Inflated or constricted - Pod colour - Green or yellow - Stem height - Tall or short
2 of 9
bull Mendel needed to control fertilisation - Self fertilisation ensured - Placed bag over flowers made sure pollen from stamens lands on carpal of same flower - Cross fertilisation ensured - Cutting off stamens before pollen was produced - Dusting carpal with pollen from another plant - Increase reliability - Mendel used thousands of plants in each experiment
bull Mendel worked with true breeding plants - Self fertilising plants - Produced offspring identical to parents 1 Mendel cross fertilised 2 true breeding plants for 1 characteristic - Eg Tall plants crossed with short plants - Mendel named these parent generation (P1) 2 Offspring produced called F1 (1st filial) generation 3 F1 generation self fertilised cross fertilised to produce F2
generation bull Each of seven traits had
- Dominant factor - Recessive factor - When 2 true breeding plants crossed only DOMINANT factor appeared in F1 - Recessive factor appeared in F2 in ratio 31 - (dominant recessive) relationship
3 of 9
Describe the aspects of the experimental techniques used by Mendel that led to his success
bull Mendel was successful because - Used peas - Easily grown - Reproduced rapidly - Selected easily observable characteristics - Strictly controlled fertilisation process - Used mathematics rigorously to analyse results - Used large number of plants - Studied traits that had 2 easily identified factors - Lucky because each trait on separate chromosome - No crossing over occurred - Not sex-linked characteristics
4 of 9
Describe outcomes of monohybrid crosses involving simple dominance using Mendels explanations
bull Monohybrid crosses involve 1 factor only - Eg Cross may involve a true breeding (homozygous) tall with a true breeding (homozygous) short plant - Produces a F1 generation where all plants are tall - Mendel explained F1 generation trait as a DOMINANT factor - Mendel explained observable ratios - Parents Homozygous tall homozygous short - F1 ALL TALL - F2 3 TALL 1 SHORT - Mendalian ratio (monohybrid ratio) 31
5 of 9
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
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- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
10 of 12
Analyse information from secondary sources to prepare a case study to show how an environmental change can lead changes in a species
The Kangaroo - Kangaroos offer a unique opportunity to study evolutionary changes within a group of Australian mammals - Have best known fossil record most extensively studied of all Aust mammals - Have undergone rapid evolutionary change - Commonly good indicators of restricted enviros - Middle of Miocene (10-12 million ya) - Aust became warmer - Aust moved north - Aridity (dryness) increased - Rainfall became seasonal - Forests changed - Dominated by eucalypts - Some pockets of open forests - Grassland thriving in drier conditions - Kangaroos became abundant - Evolving to take advantage of variety of new environments emerging from changes - Dominated grasslands - Increased in size - Rapidly diversified - Kangaroos of this age show hopping - 5th toe adaptation to arboreal (live in trees) life lost - Fossils show adaptations to grazing life - Pliocene (5-2 million ya) - Continent continued to dry out at faster rate - Rainforest restricted to east coastal regions - Woodlands grasslands replaced rainforests in central Aust
11 of 12
- End of Pliocene - Evolved bounding strides - Take advantage of vast grasslands in arid areas - Important adaptation - Pleistocene (16 million ya) to present - Kangaroos at most diverse - Varied from giant kangaroos to small types - Adapted to variety of enviros - Grasslands led to development of specialised teeth - Increased tempoC led to larger kangaroos
Use available evidence to Analyse using a named example how advances in technology have changed scientific thinking about evolutionary relationships
bull Technological changes - Up until 1950rsquos relationships between organisms worked out by - Anatomical similarities - Became possible to analyse protein sequence data amp DNA sequence data - Proteins (Eg Haemoglobin) compared amp similarities discovered based on biochemical similarities - Rate of change estimated - Possible to work out molecular clock - Estimates when 2 organisms shared common ancestors Eg Similarities between humans chimpanzees worked out by comparing amino acid sequences in DNA
12 of 12
Analyse information from secondary sources on the historical development of theories of evolution and use available evidence to assess social and political influences on these developments
bull 1735 - Linnaeus - Published classification system - Humans apes classified together - No idea of evolution in classification though strongly contested
bull Late 1700s - Erasmus Darwin (grandpa Darwin) - Suggested life came from single source
bull 1809 - Lamarck - 1st theory of evolution - Variation developed due to lsquousersquo amp lsquodisusersquo - Changes passed onto offspring - Theory proved incorrect - Challenged creationism - Helped Darwinrsquos ideas be recognised
bull 1859 - Darwin - Published lsquoOn the Origins of Species by Means of Natural Selection - In 1871 applied theory to humans in lsquoDescent of Manrsquo
bull Early 1900s - Scientists refined Darwinrsquos theory
bull Social political influences - Up until Darwinrsquos theory - Predominant Western view creationism - Diversity of living things created for enviro at same time by God in 6 days remain unchanged unrelated - Despite mounting evidence Darwinrsquos theory still rejected by religious groups - Darwinrsquos theory of descendants from apes caused political social outrage
1 of 9
HSC Biology Core 2 ndash Blueprint of Life
Focus 2
Gregor Mendels experiments helped advance our knowledge of the inheritance of characteristics
Outline the experiments carried out by Gregor Mendel
bull Mendel studied heredity bull 1860rsquos Gregor Mendel
- Formulated principles of genetics - Through careful methodical experimentation with garden peas - Garden peas have short reproductive cycle - Easily distinguishable characteristics - Easy to grow
bull Bred each variety for 2 yrs ensure pure breeding bull Crossed 1 variety with another
- Observed result in next generation bull Mendel examined
- Flower colour - Purple or white - Flower position - Axial or terminal - Seed shape - Round or wrinkled - Seed colour - Green or yellow - Pod shape - Inflated or constricted - Pod colour - Green or yellow - Stem height - Tall or short
2 of 9
bull Mendel needed to control fertilisation - Self fertilisation ensured - Placed bag over flowers made sure pollen from stamens lands on carpal of same flower - Cross fertilisation ensured - Cutting off stamens before pollen was produced - Dusting carpal with pollen from another plant - Increase reliability - Mendel used thousands of plants in each experiment
bull Mendel worked with true breeding plants - Self fertilising plants - Produced offspring identical to parents 1 Mendel cross fertilised 2 true breeding plants for 1 characteristic - Eg Tall plants crossed with short plants - Mendel named these parent generation (P1) 2 Offspring produced called F1 (1st filial) generation 3 F1 generation self fertilised cross fertilised to produce F2
generation bull Each of seven traits had
- Dominant factor - Recessive factor - When 2 true breeding plants crossed only DOMINANT factor appeared in F1 - Recessive factor appeared in F2 in ratio 31 - (dominant recessive) relationship
3 of 9
Describe the aspects of the experimental techniques used by Mendel that led to his success
bull Mendel was successful because - Used peas - Easily grown - Reproduced rapidly - Selected easily observable characteristics - Strictly controlled fertilisation process - Used mathematics rigorously to analyse results - Used large number of plants - Studied traits that had 2 easily identified factors - Lucky because each trait on separate chromosome - No crossing over occurred - Not sex-linked characteristics
4 of 9
Describe outcomes of monohybrid crosses involving simple dominance using Mendels explanations
bull Monohybrid crosses involve 1 factor only - Eg Cross may involve a true breeding (homozygous) tall with a true breeding (homozygous) short plant - Produces a F1 generation where all plants are tall - Mendel explained F1 generation trait as a DOMINANT factor - Mendel explained observable ratios - Parents Homozygous tall homozygous short - F1 ALL TALL - F2 3 TALL 1 SHORT - Mendalian ratio (monohybrid ratio) 31
5 of 9
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
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XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
11 of 12
- End of Pliocene - Evolved bounding strides - Take advantage of vast grasslands in arid areas - Important adaptation - Pleistocene (16 million ya) to present - Kangaroos at most diverse - Varied from giant kangaroos to small types - Adapted to variety of enviros - Grasslands led to development of specialised teeth - Increased tempoC led to larger kangaroos
Use available evidence to Analyse using a named example how advances in technology have changed scientific thinking about evolutionary relationships
bull Technological changes - Up until 1950rsquos relationships between organisms worked out by - Anatomical similarities - Became possible to analyse protein sequence data amp DNA sequence data - Proteins (Eg Haemoglobin) compared amp similarities discovered based on biochemical similarities - Rate of change estimated - Possible to work out molecular clock - Estimates when 2 organisms shared common ancestors Eg Similarities between humans chimpanzees worked out by comparing amino acid sequences in DNA
12 of 12
Analyse information from secondary sources on the historical development of theories of evolution and use available evidence to assess social and political influences on these developments
bull 1735 - Linnaeus - Published classification system - Humans apes classified together - No idea of evolution in classification though strongly contested
bull Late 1700s - Erasmus Darwin (grandpa Darwin) - Suggested life came from single source
bull 1809 - Lamarck - 1st theory of evolution - Variation developed due to lsquousersquo amp lsquodisusersquo - Changes passed onto offspring - Theory proved incorrect - Challenged creationism - Helped Darwinrsquos ideas be recognised
bull 1859 - Darwin - Published lsquoOn the Origins of Species by Means of Natural Selection - In 1871 applied theory to humans in lsquoDescent of Manrsquo
bull Early 1900s - Scientists refined Darwinrsquos theory
bull Social political influences - Up until Darwinrsquos theory - Predominant Western view creationism - Diversity of living things created for enviro at same time by God in 6 days remain unchanged unrelated - Despite mounting evidence Darwinrsquos theory still rejected by religious groups - Darwinrsquos theory of descendants from apes caused political social outrage
1 of 9
HSC Biology Core 2 ndash Blueprint of Life
Focus 2
Gregor Mendels experiments helped advance our knowledge of the inheritance of characteristics
Outline the experiments carried out by Gregor Mendel
bull Mendel studied heredity bull 1860rsquos Gregor Mendel
- Formulated principles of genetics - Through careful methodical experimentation with garden peas - Garden peas have short reproductive cycle - Easily distinguishable characteristics - Easy to grow
bull Bred each variety for 2 yrs ensure pure breeding bull Crossed 1 variety with another
- Observed result in next generation bull Mendel examined
- Flower colour - Purple or white - Flower position - Axial or terminal - Seed shape - Round or wrinkled - Seed colour - Green or yellow - Pod shape - Inflated or constricted - Pod colour - Green or yellow - Stem height - Tall or short
2 of 9
bull Mendel needed to control fertilisation - Self fertilisation ensured - Placed bag over flowers made sure pollen from stamens lands on carpal of same flower - Cross fertilisation ensured - Cutting off stamens before pollen was produced - Dusting carpal with pollen from another plant - Increase reliability - Mendel used thousands of plants in each experiment
bull Mendel worked with true breeding plants - Self fertilising plants - Produced offspring identical to parents 1 Mendel cross fertilised 2 true breeding plants for 1 characteristic - Eg Tall plants crossed with short plants - Mendel named these parent generation (P1) 2 Offspring produced called F1 (1st filial) generation 3 F1 generation self fertilised cross fertilised to produce F2
generation bull Each of seven traits had
- Dominant factor - Recessive factor - When 2 true breeding plants crossed only DOMINANT factor appeared in F1 - Recessive factor appeared in F2 in ratio 31 - (dominant recessive) relationship
3 of 9
Describe the aspects of the experimental techniques used by Mendel that led to his success
bull Mendel was successful because - Used peas - Easily grown - Reproduced rapidly - Selected easily observable characteristics - Strictly controlled fertilisation process - Used mathematics rigorously to analyse results - Used large number of plants - Studied traits that had 2 easily identified factors - Lucky because each trait on separate chromosome - No crossing over occurred - Not sex-linked characteristics
4 of 9
Describe outcomes of monohybrid crosses involving simple dominance using Mendels explanations
bull Monohybrid crosses involve 1 factor only - Eg Cross may involve a true breeding (homozygous) tall with a true breeding (homozygous) short plant - Produces a F1 generation where all plants are tall - Mendel explained F1 generation trait as a DOMINANT factor - Mendel explained observable ratios - Parents Homozygous tall homozygous short - F1 ALL TALL - F2 3 TALL 1 SHORT - Mendalian ratio (monohybrid ratio) 31
5 of 9
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
12 of 12
Analyse information from secondary sources on the historical development of theories of evolution and use available evidence to assess social and political influences on these developments
bull 1735 - Linnaeus - Published classification system - Humans apes classified together - No idea of evolution in classification though strongly contested
bull Late 1700s - Erasmus Darwin (grandpa Darwin) - Suggested life came from single source
bull 1809 - Lamarck - 1st theory of evolution - Variation developed due to lsquousersquo amp lsquodisusersquo - Changes passed onto offspring - Theory proved incorrect - Challenged creationism - Helped Darwinrsquos ideas be recognised
bull 1859 - Darwin - Published lsquoOn the Origins of Species by Means of Natural Selection - In 1871 applied theory to humans in lsquoDescent of Manrsquo
bull Early 1900s - Scientists refined Darwinrsquos theory
bull Social political influences - Up until Darwinrsquos theory - Predominant Western view creationism - Diversity of living things created for enviro at same time by God in 6 days remain unchanged unrelated - Despite mounting evidence Darwinrsquos theory still rejected by religious groups - Darwinrsquos theory of descendants from apes caused political social outrage
1 of 9
HSC Biology Core 2 ndash Blueprint of Life
Focus 2
Gregor Mendels experiments helped advance our knowledge of the inheritance of characteristics
Outline the experiments carried out by Gregor Mendel
bull Mendel studied heredity bull 1860rsquos Gregor Mendel
- Formulated principles of genetics - Through careful methodical experimentation with garden peas - Garden peas have short reproductive cycle - Easily distinguishable characteristics - Easy to grow
bull Bred each variety for 2 yrs ensure pure breeding bull Crossed 1 variety with another
- Observed result in next generation bull Mendel examined
- Flower colour - Purple or white - Flower position - Axial or terminal - Seed shape - Round or wrinkled - Seed colour - Green or yellow - Pod shape - Inflated or constricted - Pod colour - Green or yellow - Stem height - Tall or short
2 of 9
bull Mendel needed to control fertilisation - Self fertilisation ensured - Placed bag over flowers made sure pollen from stamens lands on carpal of same flower - Cross fertilisation ensured - Cutting off stamens before pollen was produced - Dusting carpal with pollen from another plant - Increase reliability - Mendel used thousands of plants in each experiment
bull Mendel worked with true breeding plants - Self fertilising plants - Produced offspring identical to parents 1 Mendel cross fertilised 2 true breeding plants for 1 characteristic - Eg Tall plants crossed with short plants - Mendel named these parent generation (P1) 2 Offspring produced called F1 (1st filial) generation 3 F1 generation self fertilised cross fertilised to produce F2
generation bull Each of seven traits had
- Dominant factor - Recessive factor - When 2 true breeding plants crossed only DOMINANT factor appeared in F1 - Recessive factor appeared in F2 in ratio 31 - (dominant recessive) relationship
3 of 9
Describe the aspects of the experimental techniques used by Mendel that led to his success
bull Mendel was successful because - Used peas - Easily grown - Reproduced rapidly - Selected easily observable characteristics - Strictly controlled fertilisation process - Used mathematics rigorously to analyse results - Used large number of plants - Studied traits that had 2 easily identified factors - Lucky because each trait on separate chromosome - No crossing over occurred - Not sex-linked characteristics
4 of 9
Describe outcomes of monohybrid crosses involving simple dominance using Mendels explanations
bull Monohybrid crosses involve 1 factor only - Eg Cross may involve a true breeding (homozygous) tall with a true breeding (homozygous) short plant - Produces a F1 generation where all plants are tall - Mendel explained F1 generation trait as a DOMINANT factor - Mendel explained observable ratios - Parents Homozygous tall homozygous short - F1 ALL TALL - F2 3 TALL 1 SHORT - Mendalian ratio (monohybrid ratio) 31
5 of 9
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
1 of 9
HSC Biology Core 2 ndash Blueprint of Life
Focus 2
Gregor Mendels experiments helped advance our knowledge of the inheritance of characteristics
Outline the experiments carried out by Gregor Mendel
bull Mendel studied heredity bull 1860rsquos Gregor Mendel
- Formulated principles of genetics - Through careful methodical experimentation with garden peas - Garden peas have short reproductive cycle - Easily distinguishable characteristics - Easy to grow
bull Bred each variety for 2 yrs ensure pure breeding bull Crossed 1 variety with another
- Observed result in next generation bull Mendel examined
- Flower colour - Purple or white - Flower position - Axial or terminal - Seed shape - Round or wrinkled - Seed colour - Green or yellow - Pod shape - Inflated or constricted - Pod colour - Green or yellow - Stem height - Tall or short
2 of 9
bull Mendel needed to control fertilisation - Self fertilisation ensured - Placed bag over flowers made sure pollen from stamens lands on carpal of same flower - Cross fertilisation ensured - Cutting off stamens before pollen was produced - Dusting carpal with pollen from another plant - Increase reliability - Mendel used thousands of plants in each experiment
bull Mendel worked with true breeding plants - Self fertilising plants - Produced offspring identical to parents 1 Mendel cross fertilised 2 true breeding plants for 1 characteristic - Eg Tall plants crossed with short plants - Mendel named these parent generation (P1) 2 Offspring produced called F1 (1st filial) generation 3 F1 generation self fertilised cross fertilised to produce F2
generation bull Each of seven traits had
- Dominant factor - Recessive factor - When 2 true breeding plants crossed only DOMINANT factor appeared in F1 - Recessive factor appeared in F2 in ratio 31 - (dominant recessive) relationship
3 of 9
Describe the aspects of the experimental techniques used by Mendel that led to his success
bull Mendel was successful because - Used peas - Easily grown - Reproduced rapidly - Selected easily observable characteristics - Strictly controlled fertilisation process - Used mathematics rigorously to analyse results - Used large number of plants - Studied traits that had 2 easily identified factors - Lucky because each trait on separate chromosome - No crossing over occurred - Not sex-linked characteristics
4 of 9
Describe outcomes of monohybrid crosses involving simple dominance using Mendels explanations
bull Monohybrid crosses involve 1 factor only - Eg Cross may involve a true breeding (homozygous) tall with a true breeding (homozygous) short plant - Produces a F1 generation where all plants are tall - Mendel explained F1 generation trait as a DOMINANT factor - Mendel explained observable ratios - Parents Homozygous tall homozygous short - F1 ALL TALL - F2 3 TALL 1 SHORT - Mendalian ratio (monohybrid ratio) 31
5 of 9
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
2 of 9
bull Mendel needed to control fertilisation - Self fertilisation ensured - Placed bag over flowers made sure pollen from stamens lands on carpal of same flower - Cross fertilisation ensured - Cutting off stamens before pollen was produced - Dusting carpal with pollen from another plant - Increase reliability - Mendel used thousands of plants in each experiment
bull Mendel worked with true breeding plants - Self fertilising plants - Produced offspring identical to parents 1 Mendel cross fertilised 2 true breeding plants for 1 characteristic - Eg Tall plants crossed with short plants - Mendel named these parent generation (P1) 2 Offspring produced called F1 (1st filial) generation 3 F1 generation self fertilised cross fertilised to produce F2
generation bull Each of seven traits had
- Dominant factor - Recessive factor - When 2 true breeding plants crossed only DOMINANT factor appeared in F1 - Recessive factor appeared in F2 in ratio 31 - (dominant recessive) relationship
3 of 9
Describe the aspects of the experimental techniques used by Mendel that led to his success
bull Mendel was successful because - Used peas - Easily grown - Reproduced rapidly - Selected easily observable characteristics - Strictly controlled fertilisation process - Used mathematics rigorously to analyse results - Used large number of plants - Studied traits that had 2 easily identified factors - Lucky because each trait on separate chromosome - No crossing over occurred - Not sex-linked characteristics
4 of 9
Describe outcomes of monohybrid crosses involving simple dominance using Mendels explanations
bull Monohybrid crosses involve 1 factor only - Eg Cross may involve a true breeding (homozygous) tall with a true breeding (homozygous) short plant - Produces a F1 generation where all plants are tall - Mendel explained F1 generation trait as a DOMINANT factor - Mendel explained observable ratios - Parents Homozygous tall homozygous short - F1 ALL TALL - F2 3 TALL 1 SHORT - Mendalian ratio (monohybrid ratio) 31
5 of 9
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
3 of 9
Describe the aspects of the experimental techniques used by Mendel that led to his success
bull Mendel was successful because - Used peas - Easily grown - Reproduced rapidly - Selected easily observable characteristics - Strictly controlled fertilisation process - Used mathematics rigorously to analyse results - Used large number of plants - Studied traits that had 2 easily identified factors - Lucky because each trait on separate chromosome - No crossing over occurred - Not sex-linked characteristics
4 of 9
Describe outcomes of monohybrid crosses involving simple dominance using Mendels explanations
bull Monohybrid crosses involve 1 factor only - Eg Cross may involve a true breeding (homozygous) tall with a true breeding (homozygous) short plant - Produces a F1 generation where all plants are tall - Mendel explained F1 generation trait as a DOMINANT factor - Mendel explained observable ratios - Parents Homozygous tall homozygous short - F1 ALL TALL - F2 3 TALL 1 SHORT - Mendalian ratio (monohybrid ratio) 31
5 of 9
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
4 of 9
Describe outcomes of monohybrid crosses involving simple dominance using Mendels explanations
bull Monohybrid crosses involve 1 factor only - Eg Cross may involve a true breeding (homozygous) tall with a true breeding (homozygous) short plant - Produces a F1 generation where all plants are tall - Mendel explained F1 generation trait as a DOMINANT factor - Mendel explained observable ratios - Parents Homozygous tall homozygous short - F1 ALL TALL - F2 3 TALL 1 SHORT - Mendalian ratio (monohybrid ratio) 31
5 of 9
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
5 of 9
Distinguish between homozygous and heterozygous genotypes in monohybrid crosses
bull Homozygous - Same Eg TT tt
bull Heterozygous - Different Eg Tt
bull Alternate factors for same characteristics - Alleles Eg Tall short alleles for height Purple white alleles for colour
bull For each characteristic - At least 2 alleles controlling phenotype - Gametes from each parent contain only 1 factor - When formed pairs of factors segregate
bull Heterozygous condition factor fully expressed - Dominant - Factor with no noticeable effect - Recessive
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
6 of 9
Explain the relationship between dominant and recessive genes and phenotype using examples
bull Phenotype - Outward appearance of organism
bull Genotype - Alleles on chromosome of organism Eg Homozygous tall plant (TT) 2 identical alleles for tall appear tall
bull Heterozygous plant with tall phenotype - Non identical alleles (Tt) - Tall = dominant - Short = recessive (not expressed)
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
7 of 9
Outline the reasons why the importance of Mendels work was not recognized until some time after it was published
bull Mendel began his work - 1858 Published results - 1866 Work undiscovered until - 1900 when others performed similar experiments
bull Unclear why his original work went unnoticed - Lived in isolated area - Not part of an established science community - Had no scientific reputation - Lived at monastery not university - Presented his paper to few insignificant people - Others could not comprehend his experiment of results yielded - Used maths amp numbers
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
8 of 9
Perform an investigation to construct pedigrees or family trees trace the inheritance of selected characteristics and discuss their current use
bull Pedigree - Family tree showing line of descent - Trace occurrence of inherited traits in - Parents amp offspring Through a number of generations
bull Circles represent females bull Squares represent males bull Line between circle amp square represent a union bull Line down represents offspring from union bull Filled symbols represent individuals displaying studied trait bull Valuable tools in genetic counselling
- Pattern of inheritance to be traced - ID of genetic diseases - Advice on probability can be made - Assess genotypes from phenotypes
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
9 of 9
Process information from secondary sources to identify and describe an example of hybridisation within a species and explain the purpose of this hybridisation
bull Hybridisation - Breeding of two different types of plants OR animals - Eg Mule - Result of union between horse amp donkey - Result has favourable characteristics from both parents - All mules sterile cannot produce offspring - Many agricultural animals plants result of hybridisation - Offspring with desirable characteristics Eg Cross breeding cattle Triticale (wheat crossed with rye) Zeedonk (zebra crossed with donkey) Liger (tiger crossed with lion) Wolphin (dolphin with whale) - Hybridisation good way of producing new plants
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
1 of 13
HSC Biology Core 2 ndash Blueprint of Life
Focus 3
Chromosomal structure provides the key to inheritance Outline the roles of Sutton and Boveri in identifying the importance of chromosomes
bull 1902 - 2 scientists credited with discovery of role of chromosome - German scientist Theodore Boveri - American microbiologist Walter Sutton
bull Boveri - Worked on sea urchins - Showed chromosomes not all the same - Full complement required for normal development of organism
bull Sutton - Worked on grasshoppers - Showed distinct entities - Even though they duplicate amp divide remain as distinct structure - Pointed out segregation recombination of genes showed similarities to chromosome behaviour - Associated behaviour of chromosomes with Mendelrsquos work on inheritance of factors - Concluded chromosomes carriers of heredity units - Units also transmitted with chromosomes - Showed - Chromosomes occur as homologous pair - Through meiosis - Chromosomes line up in pairs each = size amp shape - Homologous pairs segregate - Every gamete receives 1 chromosome from each pair - Chromosomes keep individuality throughout cell division - Distribution of members of homologous pair independent of that of
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
2 of 13
each pair - Since heredity factors more numerous than chromosomes - Each chromosome contains many units - Sutton also developed hypothesis - Mendelrsquos results explained on assumption genes were part of chromosomes
bull Work became known as Sutton-Boveri chromosome hypothesis
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
3 of 13
Describe the chemical nature of chromosomes and genes
bull Chromosomes - 40 DNA - Double stranded helical molecule - Made up of sub-units - Nucleotides - Sugar phosphate base - Sugar = deoxyribose (ribose lost an O atom) - Bases = Adenine Thymine Guanine Cytosine - 60 protein (histone) - DNA coiled tightly around protein - DNA approx 2m long - Short lengths of DNA make up genes - Genes have = structure to DNA
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
4 of 13
Identify that DNA is a double-stranded molecule twisted into a helix with each strand comprised of a sugar-phosphate backbone and attached bases adenine (A) thymine (T) cytosine (C) and guanine (G) connected to a complementary strand by pairing the bases A-T and G-C
bull DNA - Nucleic acid - Shape of double helix - Each strand of helix consists of 4 different nucleotides made of deoxyribose sugar PO4 molecule N base - Twisted ladder - Sides of ladder made of sugar phosphate molecules - Bases form rungs complementary - Only matching bases pair up (A-T G-C)
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
5 of 13
Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes
bull Chromosomes - Made of DNA which forms genes
bull During cell division - Each chromosome replicates itself - New chromosome attached to old at centromere (centre) - Initial meiosis division - Homologous chromosomes line up with matching pair 1 of each pair moves into new cell - Duplicated chromosomes separate resulting in 4 sex cells that contain frac12 number of chromosomes
bull Genes located on chromosomes - Duplicated during 1st stage of meiosis - Randomly assorted depending on which enters haploid cell during 1st amp 2nd division
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
6 of 13
Explain the role of gamete formation and sexual reproduction in variability of offspring
bull Gamete formation results in - Halving number of chromosomes (haploid)(n)
bull Sexual reproduction results in - Combining gametes to create a diploid (2n) organism
bull Processes involved result in variation of offspring bull Gametes formed through meiosis
- 2 stages variability - Random segregation - Crossing over
bull Sexual reproduction - Each male female produces 4 sex cells through meiosis - Each has - frac12 normal number of chromosomes - Random assortment of genes from parent - Alleles separated - Random assortment of dominant amp recessive genes - Resulting embryo genetically different from parents
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
7 of 13
Describe the inheritance of sex-linked genes and genes that exhibit co-dominance and Explain why these do not produce simple Mendelian ratios
bull Codominance - Shown in monohybrid cross when both alleles of homozygous parents expressed in heterozygous offspring
bull Sex genetically determined characteristic - Humans have 46 chromosomes in 23 pairs - 22 pairs + 1 pair of sex chromosomes - Females both X - Males XY
bull Mendel fortunate - All factors studied had dominantrecessive characteristics - 2 Egrsquos not showing Mendelian ratio are - Sex linked genes - Co-dominant genes
bull Colour blindness in humans - Sex linked inheritance - Carried on X chromosome - No corresponding gene on Y chromosome Males need only 1 allele for colour blindness females need 2 - Many more males colour blind than females
Male Colour blind Female Normal
XN XN
Xn XNXn XNXn Y XNY XNY
- All offspring have normal vision - If female carrier for colour blindness crosses with male 50 of males will have colour blindness none of females
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
8 of 13
XN Xn
XN XNXN XNXn
Y XNY XnY
bull Co-dominance gives different result than Mendelian ratio Eg Human blood types - When male with alleles AA crosses with female alleles BB - Offspring AB (different phenotype both dominant)
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
9 of 13
Describe the work of Morgan that led to the identification of sex linkage
bull 1910 bull Thomas Morgan
- Worked on fruit fly - Drosophila melangaster - Repeat Mendelrsquos work using an animal - To answer questions about variations in inherited characteristics - He looked at crosses between red-eyed amp white-eyed flies - Found results not accounted for by simple monohybrid crosses - Showed genes were sex-linked - Located on X chromosome
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
10 of 13
Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co-dominance
bull Individual has 2 different alleles (heterozygous)
- Usual case - One will be dominant - Other not expressed - Recessive - Some cases - Dominance of 2 alleles - Both alleles expressed in phenotype Eg Of Co-Dominance Human blood type - 3 alleles - A amp B - Co-dominant - o - Recessive
Alleles Blood Type AA Ao A BB Bo B
oo o AB AB
Eg Of Co-Dominance Cattle coat colour - Have allele for red amp white hair - Neither completely dominant - Mixture of both expressed as phenotype - Red cattle - RR - White cattle - WW - All F1 have roan coat
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
11 of 13
- Mix of red amp white R R
W RW RW W RW RW - Roan cattle crossed R W R RR RW W RW WW - frac12 offspring roan - frac14 red - frac14 white
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
12 of 13
Outline ways in which the environment may affect the expression of a gene in an individual
bull Identical twins - Have identical genotype - Enviro can effect - Height - Weight - Fitness level - Cultural interests - Enviro includes - Diet - Exercise - Experiences - Enviro impacts on the way a genotype is expressed - Twins that have been separated have more apparent differences
bull Height in humans
- Determined by interaction of genes amp enviro - Modern medicine amp nutrient- rich foods increased avg height - Nutrition most influencing Eg Japanese population in America - Taller than Japanese inhabitants - More nutritious foods - Japanese taller - Intro of foreign foods
bull Soil pH on Hydrangeas
- Raising pH (slightly acidic) - Blocks out bluing effect of Al - Pink flower - Lower pH (slightly basic) - Allows Al in - Blue flower - Strength of colour determined by genetics amp plantrsquos heredity
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
13 of 13
Process information from secondary sources to Construct a model that demonstrates meiosis and the processes of crossing over segregation of chromosomes and the production of haploid gametes
bull Process of crossing over - (Swapping of chromatid parts of homologous chromosomes early in meiosis) - Chromosomes duplicate - Duplicated chromosomes match in homologous pairs - Crossing over of genetic material (Shown below)
- Segregation of duplicated chromosomes - Halving number of chromosomes in each cell - Lining up of duplicated chromosomes across middle of new cells - Separation of chromatids - Formation of gametes - 8 possible combinations
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
Page 1 of 12
HSC Biology Core 2 ndash Blueprint of Life
Focus 4
The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism
Describe the process of DNA replication and Explain its significance The Process of DNA Replication
bull DNA - Double stranded molecule - Twisted into helix - Each strand - Sugar ndash phosphate backbone - Bases attached - Adenine-Tymine - Cytosine-Guanine
bull A unit made of deoxyribose sugar phosphate molecule 1 of 4 nitrogen bases - Each unit Nucleotide - Nitrogen bases form rungs of DNA double helix
bull Along DNA molecule - Sequences of genetic code made up of bases - Replication of sequences account for replication of genetic code of an organism
bull DNA replication - DNA double helix unwound by an enzyme - DNA unzips forming 2 single strands - Bonds break between each helix - Forming Replication Fork - Binding proteins prevent strands rejoining - Complementary copy of strand constructed - From new sugar-phosphate-base units - Process catalysed by enzyme DNA polymerase - One strand built as a continuous strand - Other built by linking DNA fragments (Okizaki frags) together
bull 2 double stranded molecules chromatids
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
Page 2 of 12
The Significance of DNA Replication bull Genetic info passed from generation to generation
- During reproduction - Genetic code copied - frac12 passes into each cell (gametes) - New organism contains frac12 genetic info from each parent
bull Identical copy of gene can be made Outline using a simple model the process by which DNA controls the production of polypeptides
bull Polypeptide synthesis involves nucleotide RNA - Intermediary between DNA amp polypeptide synthesis - Single strand of nucleotide bases - Consists of - Ribose sugar - Thymine replaced by Uracil - Combines with Adenine
bull 2 types RNA involved in polypeptide synthesis - Messenger RNA (mRNA)
- Carries info from DNA in nucleus to ribosomes in cytoplasm
- Transfer RNA (tRNA) - Brings AArsquos to ribosomes to be linked together to build a protein - 20+ types of tRNA - Different type for each AA - Each contains anticodon which recognises amp is complementary to a codon on mRNA
bull In the nucleus
- DNA molecules unzip - DNA code transcribed into single stranded mRNA molecule - Enzyme RNA polymerase provides required energy - mRNA moves into cytoplasm attaches to a ribosome
bull In cytoplasm - mRNA translated into AArsquos
bull At ribosome - mRNA lines up - Forms a template - A group of 3 bases - A CODON - Codes for a specific AA
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
Page 3 of 12
- Codes for starting amp stopping chain formation - AUG - Starting point for translation - tRNA - Has ANTICODON - Non AA forming codon on one end amp an AA on the other end - Polypeptide formed when - Each AA added from tRNA to a chain following sequence on mRNA
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
Page 4 of 12
Explain the relationship between proteins and polypeptides
bull Polypeptide - Made of a chain of 2 or more AArsquos
bull Protein - Made of one or more polypeptides
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
Page 5 of 12
Explain how mutations in DNA may lead to the generation of new alleles
bull Mutation - Change in DNA info on a chromosome
bull Any change to base sequence in DNA results in changes to polypeptides produced - Source of new alleles
bull To produce new alleles - Mutation must occur in sex cells or organism - Passed onto next generation
bull Mutations in body cells - Change organism - Not passed on
bull Changes in DNA sequences occur when - One base replaced by another Eg A in place of C - Causes change in code for AA - Extra nucleotide added to the 3-base code sequence - Whole sequence of AArsquos changed - Structure changed - Protein synthesis significantly altered - Chromosome broken rearranged
bull Types of DNA change - Deletion - Some of DNA lost from chromosome - Duplication - Extra copy of a sequence made on a chromosome - Inversion - DNA sequence breaks reattached in wrong way - Translocation - DNA joins to another chromosome - Amplification - Many extra copies of DNA made on a chromosome - Positive effect - Changed DNA sequence affects genes next to or near it
Discuss evidence for the mutagenic nature of radiation
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
Page 6 of 12
bull Much evidence for mutagenic nature of radiation bull Enviro factors that increase rate of mutation
- X-rays - Radiation from A bombs - UV light
bull Mutagen - Natural man-made agent (phys chem) which can alter structure sequence of DNA - Can be - Carcinogens - Cancer causing - Teratogens - Birth defect causing
bull Radiation 1st mutagenic agent known - Effects on genes first noticed in 1920rsquos - When X-rays discovered - Thought to be harmless - Were a great novelty - Able to buy lsquohome X-rayrsquo machine for entertainment - Most first generation scientists working with radiation died of cancer Eg Marie Curie amp daughter died of leukemia
bull Hans Muller - Received Nobel Prize 1927 - Showing genes had ability to mutate when exposed to X-rays
bull Beadle amp Tatum - Used X-rays to produce mutations in bread mould to formulate lsquoOne gene one polypeptidersquo hypothesis
bull A bombs dropped on Hiroshima amp Nagasaki - Increased evidence of mutations from radiation - Large increase of cancer deaths directly after bombs dropped
bull Mutagens may cause death in individual - Unless affect sex-cell cannot be passed on to offspring
Explain how an understanding of the source of variation in organisms has provided support for Darwinrsquos theory of
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
Page 7 of 12
evolution by natural selection
bull One foundation pillar for theory of evolution - Variation occurs among individual members of a species - Selection acts upon variation - Mutation of DNA provides source for variation - Supporting Darwinrsquos theory for evolution
Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
Page 8 of 12
bull Darwinrsquos theory of gradual evolution - Evolution over long period of time - Little change in organism - Followed by short period of rapid changes
bull Punctuated equilibrium - Sudden process - Rather than slow gradual change
bull Evidence derived from fossil records - Mass extinctions - Appearance of new species
Analyse information from secondary sources to Outline the evidence that led to Beadle and Tatumrsquos lsquoone gene ndash one
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
Page 9 of 12
proteinrsquo hypothesis and to Explain why this was altered to the lsquoone gene ndash one polypeptidersquo hypothesis
bull Beadle amp Tatum - Developed techniques to - Screen - Detect nutritional mutants in pink bread mould (Neurospora crassa) - Mutated mould created by x-rays - Each strain lacked ability to produce particular aa or vitamin - Showed link between biochemical processes amp genes -Suggested lsquoone gene ndash one enzymersquo hypothesis - Each biochemical reaction controlled by a gene - May be true for some enzymes not all
bull Altered to lsquoone gene ndash one polypeptidersquo hypothesis - 1 gene is the portion of DNA specifying single polypeptide chain - Several genes usually required to specify enzyme involved in biochemical process - Even simple pathways Eg Enzyme tryptophan synthetase consists of 2 structurally different protein chains - Produced by different DNA segments
Process information to Construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
Page 10 of 12
bull Cell activity controlled by - Enzymes - Formed from chains of polypeptides - If chain is not in right sequence - Enzyme formed = dysfunctional - Diagram above demonstrates a premature stop
Process and Analyse information from secondary sources to Explain a modern example of lsquonaturalrsquo selection
DNA
mRNA
AA
Polypeptide
TAC GTC TAT TTG CGA CGT ATT
AUG CAG AUA AAC GCU GCA UAA
met gin lle asn ala ala stop
Functional Enzyme
ACG TCT ATT TGC GAC GTA TT
UGC AGA UAA ACG CUG CAU AA
cis arg stop
Dysfunctional Enzyme
Loss of thymine at start
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
Page 11 of 12
bull Insecticide resistance in insect pests - Species laying large numbers of eggs - Reproduce several times in a mating season - Insect species
bull More likely to have offspring with genetic mutation - Can result in genetic mutation for survival
bull Natural pop of insects - Variety of characteristics - By chance some insects more resistant to insecticide
bull When insect pop first sprayed - Most will die - Those with genetic resistance survive
bull Resistant insects reproduce - Pass on genetic characteristics - Some inherit resistance others donrsquot
bull Proportion of resistant insects increases with each generation
Process Information from secondary sources to Describe and Analyse the relative importance of the work of
bull James Watson bull Francis Crick
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
Page 12 of 12
bull Rosalind Franklin bull Maurice Wilkins
in determining the structure of DNA and the impact of the quality of collaboration and communication on their scientific research
bull Discovery of structure of DNA in 1953
- Most significant scientific achievement of 20th Century - Example of how scientists collaborate work internal conflicts amp clashes influence effective communication in scientific research
bull Main scientists responsible for discovery - Rosalind Franklin - Maurice Wilkins
bull Franklin - Contributed development of x-ray crystallography - Method of determining structure of crystals - Based on use of x-rays - Locations of atoms in crystals mapped - Can be used to look at DNA - Used technique - X-ray diffraction - Showed DNA had characteristics of a helix - Suspected all DNA had helix structure - Held back on announcement until sufficient evidence - Worked alone didnrsquot get on with Wilkins
bull Wilkins - Showed Franklinrsquos work to Watson without her knowledgeconsent
bull Watson amp Crick - Produced a failed model - Told to stop DNA research - Convinced of 3D structure - DNA could be determined - Way genes passed on could then be determined - Close working relationship
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
1 of 6
HSC Biology Core 2 ndash Blueprint of Life
Focus 5
Current reproductive technologies and genetic engineering have the potential to alter the path of evolution
Identify how the following current reproductive techniques may alter the genetic composition of a population
o artificial insemination o artificial pollination o cloning
bull Artificial insemination - Injection of male semen into female - Commonly used by - Animal breeders - Cows - Sheep - Sperm collected from male with desirable characteristics - Can be transported large distances - Many females fertilised - More offspring produced
bull Artificial pollination - Plants pollinated by hand - Dusting fertile stigmas with pollen from plants with desirable characteristics - Allow genetic changes quickly widespread within populations
bull Cloning - Produce genetically identical organisms - Genes cells organisms may be cloned - All asexual reproduction produces clones - Cloning of plants by cuttinggrafting used for years - Produce identical cropsgardens - Tissue culture techniques used to produce clones of plants with required characteristics - Animal cloning offered challenge to scientists - Large domestic animals prove hardest challenge - Dolly cloned by nuclear transfer technology
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
2 of 6
bull In all reproductive methods donor gametesbody cells carefully selected for predetermined characteristics - Leads to genetic variation being reduced over generations
Outline the processes used to produce transgenic species and include examples of this process and reasons for its use
bull Genetic engineering - Producing a transgenic species
bull Transgenic species - Contain a gene from another species
bull Isolating genes - Useful gene identified isolated by cutting out of DNA strand - Restriction enzymes or endonucleases used for this - AKA gene scissors - Found in bacteria 800+ types known - Each enzyme cuts sequence of nucleotides at a specific point - Cut ends known as lsquosticky endsrsquo
bull Recombinant DNA - DNA strands from 2 different organisms cut with same enzyme mixed - Matching sticky ends connect - Annealing - Ligases sealing amp strengthening enzymes - Found in all living organisms - Make amp repair DNA - Seal amp strengthen annealing DNA fragments - Producing recombinant DNA
bull Producing transgenes - Genes contain a code for a specific protein - When new protein required - mRNA only copies the code - DNA strand contains controlpromoter sequences - Switch gene lsquoonrsquo or lsquooffrsquo - Regulate production of protein - When - How much - Where (which cell) it will function - An isolated gene cannot function alone - Requires promoter sequence
bull Copying genes - Genetic engineering on a large scale - Multiple copies of genes produced
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
3 of 6
- Polymerase chain reactions (PCR) do this - DNA molecule with required gene - Large amount of nucleotide bases - Adenine - Thymine - Guanine - Cytosine - DNA polymerase - Primers - Short nucleotide sequences - Initiate process mixed together - Mixture heated - Separates double stranded DNA molecule - Cooled - Primers anneal to ends of DNA strands - DNA polymerase synthesises complementary DNA strands - Doubles number of DNA molecules in 2 minutes - Repetition of heating cooling rapidly produces large quantities of DNA
bull Inserting gene into bacteria - Plasmids - Small circular pieces contained by bacteria - Used as vectors (carriers) - Transfer transgenes to bacteria - Inserted into bacteria - Bacteria treated with cold calcium chloride then heat - Softens bacterial wall easier penetration - Bacteria rapidly clone isolated gene - Human insulin amp HGH genes inserted into bacteria - Bacteria cultured - Hormones produced harvested used to treat people - Bacteriophages - Viruses infecting bacteria - Used to insert genes
bull Genes into plants - Ti (tumour inducing) plasmid insertion - Agrobacterium tumefaciens - Causes a tumour containing transgene to grow in plant - Makes copies as tumour grows
bull Genes into animal cells - Microinjection - Uses fine glass pipettes
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
4 of 6
bull Insertion using geneparticle gun - Shoot DNA coated metal pellets into cells of animals or plants
Eg Genetically engineered salmon - Inserted with protein BGH (bovine growth hormone) Eg Potato plants inserted with gene for lectin from peas - Creates crops resistant to some pests
Discuss the potential impact of the use of reproduction technologies on genetic diversity of species using a named plant and animal example that have been genetically altered
bull Reproductive techniques - Cloning - Engineering of transgenic species have ability to - Increase genetic diversity - Decrease genetic diversity - Moving genes from species to species increases genetic diversity - Rice crops genetically engineered to suit climate amp topography resistance to herbicides used in a region - Transgenic species present larger problems with a - Cloning reduces genetic diversity offspring are identical
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
5 of 6
Process information from secondary sources to Describe a methodology used in cloning organisms
bull The process of producing genetically identical offspring - In the absence of sexual reproduction - Plants amp animals already successfully cloned
bull Plants cloned through tissue propagation - Root tissue taken - Cells separated - Cells cultured in a nutrient rich environ - Become unspecialised - Calluses - Calluses treated with plant hormones - Develop into seedlings - Grow into fully matured plants - Genetically identical to lsquoparentrsquo plant Eg Wollemi Pine - Recently discovered in Blue Mountains after believed extinct - Cloned - Offspring sent to botanical gardens sold to public
bull Animal cloning - Progress not rapid - Requires unfertilised egg as a host for genetic material - Donor egg has nucleus removed - Nucleus from cell of species to be cloned inserted - Electrical stimulus fuses egg with nucleus initiates cell division - Embryo inserted into surrogate mother continues to develop - Offspring genetically identical to animal that donated nucleus - First performed 1970rsquos - Tadpoles cloned - Didnrsquot grow into frogs - Dolly 1st cloned mammal 1997
Analyse Information from secondary sources to Identify examples of the use of transgenic species and Use Available evidence to debate the ethical issues arising from the development and use of transgenic species
bull Eg - Transgenic tomatoes - Improved shelf life - Less wasted food reduce costs to consumers stores Eg - Transgenic soya beans imported into Australia - Resistant to Roundup (herbicide) - More yield from crop - Lower cost to farmer
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
6 of 6
- No destroyed plants Eg - lsquoSuper pigrsquo - 10 extra growth hormones - Genes engineered from human DNA - Genes lsquoswitched onrsquo in presence of Zn - Allows supply of meat to meet its demands Eg - Transgenic sheep - Able to secrete alpha-1 - Protein to treat human lung disease
bull Ethical issues - Should something be done just because its possible - Long term effects on transgenic species - Cows treated with genetically engineered BGH increase milk production - Possible health risk to humans - Risk of mastitis - Infection of nipple - Cows given antibiotics to counter react - Moral questions about creating transgenic species - Raised by animal rights activists - Lab mice bred to automatically develop diseases for scientific study - Cancer cystic fibrosis muscular dystrophy - Concern over return of eugenics movement - Strategy applying to selective breeding of desirable traits - Sterilising the mentally retarded - Similar to actions of NAZI Germans - Genetically engineered organisms in environ cause disease - Transgenic species may cause new diseases - Create strains of resistant diseases - Health Risks - Genetically modified foods may cause harm when eaten
- t2f1
- t2f2
- t2f3
- t2f4
- t2f5
top related