Genetics notes

Genetics

Hemophilia

• An inherited blood disorder that slows the blood clotting process

• This means that the factors that cause the blood to clot are missing

• In the past life expectancy was age 11 but now it is only about 10 years less than average

• Hemophilia is a sex linked disorder, it is found on the X chromosome

• (Remember females are XX and males are XY)

• A mother who is a carrier has a 50% chance of passing the faulty chromosome to her daughter

• An affected father will always pass on the affected gene to his daughter

Klinefelter’s Syndrome

• Condition in which males have an extra X chromosomes

• Most common sex chromosome disorder

• Affected males usually are infertile, some degree of language learning impairment may be present, as well they may have more feminine body characteristics

What is the difference between sex

chromosomes and somatic chromosomes?

• Sex Chromosomes: X and Y, these chromosomes code for sex characteristics

• Somatic Chromosomes: 1-22, these code for all other characteristics in the body regardless of sex

Asexual Reproduction

• Type of reproduction that involves only one parent

• Produces offspring that are generally identical to the parent

• Asexual reproduction is beneficial because it allows populations to continue even if their is a lack of males

• The downside is that because offspring are identical to parents, genetic variation is lacking and the population is susceptible to disease

• e.g. Bananas

Sexual Reproduction

• Reproduction involving the union or fusion of a male and female gamete

• Because 1/2 of the genetic material comes from each parent there is much more genetic variation within offspring

Biotechnology in our Society

Recombinant DNA

• Type of DNA that is artificially created by inserting a strand or more of DNA into a different set of DNA

• Called rDNA

• Used to introduce specific characteristics into different crops, bacteria and animals

• commonly used to create strains of crops that are draught resistance, etc

• 1. Isolate gene

• 2. Prepare target DNA, a circular piece of DNA(called plasmid) is taken from one organism, special proteins are used to cut open the DNA

• 3. Insert DNA into Plasmid, the gene that is being inserted is put into the plasmid ring and the ring is closed again

Steps in Creating Recombinant DNA

• 4. Insert Plasmid back into cell, the DNA that contains the human gene is inserted into a bacteria

• 5. Plasmid multiply, when the bacteria multiplies, whatever the new gene codes for presents itself in the new offspring

• 6. Target cells reproduce

• 7. Cells produce proteins

Genetic Screening

• Process that allows for the identification of inherited diseases, paternity, mutations, etc

Adult

• Can be used in presymptomatic testing for adult-onset disorders like Huntington’s or for estimating the risk of developing adult-onset cancers or Alzheimers

pre-natal testing

• Ultrasound-can be used to check for abnormal development

• Amniocentesis-a sample of amniotic fluid is taken, can be used to check for Downs syndrome, neural tube defects, etc

• Karyotype-done with samples taken from amniocentesis etc

Explain why you think genetic testing can have

positive effects and negative effects in a

paragraph

Population Genetics

deme and gene pool

• Deme-a term for an isolated population that interbreed with each other and share a distinct gene pool

• Gene pool-the complete set of unique alleles in a population

• a large gene pool indicates extensive genetic diversity, this means that the population will be able to withstand disease, etc

• a small gene pool can lead to deme’s which can lead to susceptibility to certain diseases etc within that population, e.g. hemophilia in the royal family, tay-sachs in Ashkenazi jewish populations, etc

Hardy-Weinberg Principle

• http://www.slideshare.net/klemmistry101/hardy-weinberg-populations

Hardy-Weinberg handout

Genetic Drift

• frequency of traits can change in a population due to chance events

• this is NOT adaptation to environmental conditions

• Occurs with the founder effect and bottleneck effect

• Founder effect: small group splinters off and starts a new colony

• just by chance some rare alleles may be at high frequency, others may be missing

• skews the gene pool of the new population

• e.g. colonization of ‘New World’-human populations that started from small groups of colonists

• Bottleneck effect: when a large population is drastically reduced by a disaster i.e. famine, natural disaster, loss of habitat

• loss of variation by chance event, alleles lost from gene pool

• this narrows the gene pool

• Bottleneck example: Cheetahs

• all share a small number of alleles-less that 1% diversity, as if ALL cheetahs are identical twins

• 2 bottlenecks-10,000 years ago(Ice Age), last 100 years (poaching and loss of habitat)

The End.