Chapter 123.6+DNA...Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor, Simon, and Dickey Chapter 12 DNA Technology and Genomics ... 4. DNA with the target ...
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© 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko
PowerPoint Lectures forCampbell Biology: Concepts & Connections, Seventh EditionReece, Taylor, Simon, and Dickey
Chapter 12 DNA Technology and Genomics
▪ DNA technology– has rapidly revolutionized the field of forensics,
– permits the use of gene cloning to produce medical and industrial products,
– allows for the development of genetically modified organisms for agriculture,
– permits the investigation of historical questions about human family and evolutionary relationships, and
– is invaluable in many areas of biological research.
Introduction
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Figure 12.0_1Chapter 12: Big Ideas
Gene Cloning
DNA Profiling
Genetically ModifiedOrganisms
Genomics
Figure 12.0_2
GENE CLONING
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12.1 Genes can be cloned in recombinant plasmids
▪ Biotechnology is the manipulation of organisms or their components to make useful products.
▪ For thousands of years, humans have– used microbes to make wine and cheese and
– selectively bred stock, dogs, and other animals.
▪ DNA technology is the set of modern techniques used to study and manipulate genetic material.
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Figure 12.1A
12.1 Genes can be cloned in recombinant plasmids
▪ Genetic engineering involves manipulating genes for practical purposes.– Gene cloning leads to the production of multiple,
identical copies of a gene-carrying piece of DNA.
– Recombinant DNA is formed by joining nucleotide sequences from two different sources.– One source contains the gene that will be cloned.
– Another source is a gene carrier, called a vector.– Plasmids (small, circular DNA molecules independent of the
bacterial chromosome) are often used as vectors.
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▪ Steps in cloning a gene1. Plasmid DNA is isolated.
2. DNA containing the gene of interest is isolated.
3. Plasmid DNA is treated with a restriction enzyme that cuts in one place, opening the circle.
4. DNA with the target gene is treated with the same enzyme and many fragments are produced.
5. Plasmid and target DNA are mixed and associate with each other.
12.1 Genes can be cloned in recombinant plasmids
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6. Recombinant DNA molecules are produced when DNA ligase joins plasmid and target segments together.
7. The recombinant plasmid containing the target gene is taken up by a bacterial cell.
8. The bacterial cell reproduces to form a clone, a group of genetically identical cells descended from a single ancestral cell.
12.1 Genes can be cloned in recombinant plasmids
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Animation: Cloning a GeneRight click on animation / Click play
Figure 12.1B E. coli bacterium
Bacterialchromosome
A plasmidis isolated.
Gene ofinterest
The plasmid is cutwith an enzyme.
Plasmid
The cell’s DNAis isolated.
The cell’s DNA is cutwith the same enzyme.
DNA
Examples of gene use
A cell with DNAcontaining the geneof interest
Geneof interest
The targeted fragmentand plasmid DNAare combined.
DNA ligase is added,which joins the twoDNA molecules.
Geneof interest
Genes may be insertedinto other organisms.
The recombinant plasmidis taken up by a bacteriumthrough transformation.
Examples of protein use
Harvestedproteinsmay beuseddirectly.
The bacteriumreproduces.
Cloneof cells
Recombinantbacterium
RecombinantDNAplasmid
1
3
5
4
2
6
7
9
8
Figure 12.1B_s1
E. colibacterium
Bacterialchromosome
A plasmidis isolated.
Gene ofinterest
Plasmid
The cell’s DNAis isolated.
DNA
A cell with DNAcontaining the geneof interest
12
Figure 12.1B_s2
E. colibacterium
Bacterialchromosome
A plasmidis isolated.
Gene ofinterest
Plasmid
The cell’s DNAis isolated.
DNA
A cell with DNAcontaining the geneof interest
1
3
2
4
The plasmid is cutwith an enzyme.
The cell’s DNA is cutwith the same enzyme.
Geneof interest
Figure 12.1B_s3
E. colibacterium
Bacterialchromosome
A plasmidis isolated.
Gene ofinterest
Plasmid
The cell’s DNAis isolated.
DNA
A cell with DNAcontaining the geneof interest
1
3
2
4
5
The plasmid is cutwith an enzyme.
The cell’s DNA is cutwith the same enzyme.
Geneof interest
The targeted fragmentand plasmid DNAare combined.
Figure 12.1B_s4
E. colibacterium
Bacterialchromosome
A plasmidis isolated.
Gene ofinterest
Plasmid
The cell’s DNAis isolated.
DNA
A cell with DNAcontaining the geneof interest
1
3
2
4
5
6
The plasmid is cutwith an enzyme.
The cell’s DNA is cutwith the same enzyme.
Geneof interest
The targeted fragmentand plasmid DNAare combined.
DNA ligase is added,which joins the twoDNA molecules.
Geneof interest
RecombinantDNAplasmid
Figure 12.1B_s5
Geneof interest
The recombinant plasmidis taken up by a bacteriumthrough transformation.
Recombinantbacterium
RecombinantDNAplasmid
7
Figure 12.1B_s6
Geneof interest
The recombinant plasmidis taken up by a bacteriumthrough transformation.
The bacteriumreproduces.
Cloneof cells
Recombinantbacterium
RecombinantDNAplasmid
7
8
Figure 12.1B_s7
Geneof interest
The recombinant plasmidis taken up by a bacteriumthrough transformation.
Harvestedproteinsmay beuseddirectly.
The bacteriumreproduces.
Cloneof cells
Recombinantbacterium
RecombinantDNAplasmid
Genes may be insertedinto other organisms.
9
7
8
12.2 Enzymes are used to “cut and paste” DNA
▪ Restriction enzymes cut DNA at specific sequences.– Each enzyme binds to DNA at a different restriction
site.
– Many restriction enzymes make staggered cuts that produce restriction fragments with single-stranded ends called “sticky ends.”
– Fragments with complementary sticky ends can associate with each other, forming recombinant DNA.
▪ DNA ligase joins DNA fragments together.
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Animation: Restriction EnzymesRight click on animation / Click play
Figure 12.2_s1
A restrictionenzyme cutsthe DNA intofragments.
Restriction enzymerecognition sequence
Restrictionenzyme
Sticky
endStick
yend
DNA1
2
Figure 12.2_s2
A restrictionenzyme cutsthe DNA intofragments.
Restriction enzymerecognition sequence
Restrictionenzyme
Gene ofinterestA DNA fragment
from anothersource is added.
Sticky
endStick
yend
DNA1
2
3
Figure 12.2_s3
A restrictionenzyme cutsthe DNA intofragments.
Restriction enzymerecognition sequence
Restrictionenzyme
Gene ofinterestA DNA fragment
from anothersource is added.
Two (or more)fragments sticktogether bybase pairing.
Sticky
endStick
yend
DNA1
2
4
3
Figure 12.2_s4
A restrictionenzyme cutsthe DNA intofragments.
Restriction enzymerecognition sequence
Restrictionenzyme
Gene ofinterestA DNA fragment
from anothersource is added.
Two (or more)fragments sticktogether bybase pairing.
Sticky
endStick
yend
DNA ligaseDNA ligasepastes thestrands together.
RecombinantDNA molecule
DNA1
2
4
5
3
12.3 Cloned genes can be stored in genomic libraries
▪ A genomic library is a collection of all of the cloned DNA fragments from a target genome.
▪ Genomic libraries can be constructed with different types of vectors:– plasmid library: genomic DNA is carried by plasmids,
– bacteriophage (phage) library: genomic DNA is incorporated into bacteriophage DNA,
– bacterial artificial chromosome (BAC) library: specialized plasmids that can carry large DNA sequences.
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Figure 12.3
A genome is cut up witha restriction enzyme
Recombinantphage DNA
Recombinantplasmid
Bacterialclone
Phageclone
or
Plasmid library Phage library
12.4 Reverse transcriptase can help make genes for cloning
▪ Complementary DNA (cDNA) can be used to clone eukaryotic genes.– In this process, mRNA from a specific cell type is the
template.– Reverse transcriptase produces a DNA strand from
mRNA.– DNA polymerase produces the second DNA strand.
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12.4 Reverse transcriptase can help make genes for cloning
▪ Advantages of cloning with cDNA include the ability to– study genes responsible for specialized characteristics
of a particular cell type and– obtain gene sequences
– that are smaller in size,– easier to handle, and– do not have introns.
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Figure 12.4
CELL NUCLEUS
DNA of aeukaryoticgene
RNAtranscript
mRNA
TEST TUBEReverse transcriptase
cDNA strandbeing synthesized
Directionof synthesis
Breakdown of RNA
Synthesis of secondDNA strand
Isolation of mRNA fromthe cell and the additionof reverse transcriptase;synthesis of a DNA strand
cDNA of gene(no introns)
Exon Exon ExonIntron Intron
Transcription
RNA splicing (removesintrons and joins exons)
1
2
3
4
5
Figure 12.4_1
CELL NUCLEUS
DNA of aeukaryoticgene
RNAtranscript
mRNA
Exon Intron
Transcription
RNA splicing (removesintrons and joins exons)
1
2
Exon Intron Exon
Figure 12.4_2
TEST TUBEReverse transcriptase
cDNA strandbeing synthesized
Directionof synthesis
Breakdown of RNA
Synthesis of secondDNA strand
Isolation of mRNA fromthe cell and the additionof reverse transcriptase;synthesis of a DNA strand
cDNA of gene(no introns)
3
4
5
12.5 Nucleic acid probes identify clones carrying specific genes
▪ Nucleic acid probes bind very selectively to cloned DNA.– Probes can be DNA or RNA sequences
complementary to a portion of the gene of interest.
– A probe binds to a gene of interest by base pairing.
– Probes are labeled with a radioactive isotope or fluorescent tag for detection.
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12.5 Nucleic acid probes identify clones carrying specific genes
▪ One way to screen a gene library is as follows:1. Bacterial clones are transferred to filter paper.
2. Cells are broken apart and the DNA is separated into single strands.
3. A probe solution is added and any bacterial colonies carrying the gene of interest will be tagged on the filter paper.
4. The clone carrying the gene of interest is grown for further study.
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Figure 12.5
Radioactivenucleic acid probe(single-stranded
DNA)
Base pairinghighlights thegene of interest.
The probe is mixed withsingle-stranded DNAfrom a genomic library.
Single-strandedDNA
GENETICALLY MODIFIED ORGANISMS
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12.6 Recombinant cells and organisms can mass-produce gene products
▪ Recombinant cells and organisms constructed by DNA technologies are used to manufacture many useful products, chiefly proteins.
▪ Bacteria are often the best organisms for manufacturing a protein product because bacteria– have plasmids and phages available for use as gene-
cloning vectors,– can be grown rapidly and cheaply,– can be engineered to produce large amounts of a
particular protein, and– often secrete the proteins directly into their growth
medium.
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12.6 Recombinant cells and organisms can mass-produce gene products
▪ Yeast cells– are eukaryotes,– have long been used to make bread and beer,– can take up foreign DNA and integrate it into their
genomes,– have plasmids that can be used as gene vectors, and– are often better than bacteria at synthesizing and
secreting eukaryotic proteins.
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12.6 Recombinant cells and organisms can mass-produce gene products
▪ Mammalian cells must be used to produce proteins with chains of sugars. Examples include– human erythropoietin (EPO), which stimulates the
production of red blood cells,
– factor VIII to treat hemophilia, and
– tissue plasminogen activator (TPA) used to treat heart attacks and strokes.
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Table 12.6
Table 12.6_1
Table 12.6_2
12.6 Recombinant cells and organisms can mass-produce gene products
▪ Pharmaceutical researchers are currently exploring the mass production of gene products by– whole animals or
– plants.
▪ Recombinant animals– are difficult and costly to produce and
– must be cloned to produce more animals with the same traits.
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Figure 12.6A
A GOAT CARRYING A GENE FOR A HUMAN BLOOD PROTEIN THAT IS SECRETED IN THE MILK
Figure 12.6B
A PIG THAT HAS BEEN GENETICALLY MODIFIED TO PRODUCE A USEFUL HUMAN PROTEIN
12.7 CONNECTION: DNA technology has changed the pharmaceutical industry and medicine
▪ Products of DNA technology are already in use.– Therapeutic hormones produced by DNA technology
include– insulin to treat diabetes and– human growth hormone to treat dwarfism.
– DNA technology is used to– test for inherited diseases,– detect infectious agents such as HIV, and– produce vaccines, harmless variants (mutants) or derivatives
of a pathogen that stimulate the immune system.
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Figure 12.7A
HUMAN INSULIN PRODUCED BY BACTERIA
Figure 12.7B
EQUIPMENT USED IN THE PRODUCTION OF A VACCINE AGAINST HEPATITIS B
12.8 CONNECTION: Genetically modified organisms are transforming agriculture
▪ Genetically modified (GM) organisms contain one or more genes introduced by artificial means.
▪ Transgenic organisms contain at least one gene from another species.
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12.8 CONNECTION: Genetically modified organisms are transforming agriculture
▪ The most common vector used to introduce new genes into plant cells is– a plasmid from the soil bacterium Agrobacterium
tumefaciens and– called the Ti plasmid.
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Figure 12.8A_s1
Restrictionsite
The gene isinserted intothe plasmid.
RecombinantTi plasmid
DNA containing thegene for a desired trait
1Ti
plasmid
Agrobacteriumtumefaciens
Figure 12.8A_s2
Restrictionsite
The gene isinserted intothe plasmid.
The recombinantplasmid isintroduced intoa plant cell. DNA carrying
the new gene
RecombinantTi plasmid
Plant cellDNA containing thegene for a desired trait
21Ti
plasmid
Agrobacteriumtumefaciens
Figure 12.8A_s3
Restrictionsite
The gene isinserted intothe plasmid.
The recombinantplasmid isintroduced intoa plant cell.
The plant cellgrows intoa plant.
DNA carryingthe new gene
A plantwith thenew trait
RecombinantTi plasmid
Plant cellDNA containing thegene for a desired trait
3
21Ti
plasmid
Agrobacteriumtumefaciens
12.8 CONNECTION: Genetically modified organisms are transforming agriculture
▪ GM plants are being produced that– are more resistant to herbicides and pests and– provide nutrients that help address malnutrition.
▪ GM animals are being produced with improved nutritional or other qualities.
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Figure 12.8B
12.9 Genetically modified organisms raise concerns about human and environmental health
▪ Scientists use safety measures to guard against production and release of new pathogens.
▪ Concerns related to GM organisms include the potential– introduction of allergens into the food supply and– spread of genes to closely related organisms.
▪ Regulatory agencies are trying to address the– safety of GM products,– labeling of GM produced foods, and– safe use of biotechnology.
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12.10 CONNECTION: Gene therapy may someday help treat a variety of diseases
▪ Gene therapy aims to treat a disease by supplying a functional allele.
▪ One possible procedure is the following: 1. Clone the functional allele and insert it in a retroviral
vector.
2. Use the virus to deliver the gene to an affected cell type from the patient, such as a bone marrow cell.
3. Viral DNA and the functional allele will insert into the patient’s chromosome.
4. Return the cells to the patient for growth and division.
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12.10 CONNECTION: Gene therapy may someday help treat a variety of diseases
▪ Gene therapy is an– alteration of an afflicted individual’s genes and– attempt to treat disease.
▪ Gene therapy may be best used to treat disorders traceable to a single defective gene.
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Figure 12.10
An RNA version ofa normal humangene is insertedinto a retrovirus.
RNA genome of virus
Retrovirus
Bone marrow cellsare infected withthe virus.
Viral DNA carrying thehuman gene inserts intothe cell’s chromosome.
Bone marrowcell from the patient
Bonemarrow
The engineeredcells are injectedinto the patient.
Cloned gene(normal allele) 1
2
3
4
Figure 12.10_1
An RNA version ofa normal humangene is insertedinto a retrovirus.
RNA genome of virus
Retrovirus
Cloned gene(normal allele) 1
Figure 12.10_2
Bone marrow cellsare infected withthe virus.
Viral DNA carrying thehuman gene inserts intothe cell’s chromosome.
Bone marrowcell from the patient
Bonemarrow
The engineeredcells are injectedinto the patient.
2
3
4
12.10 CONNECTION: Gene therapy may someday help treat a variety of diseases
▪ The first successful human gene therapy trial in 2000– tried to treat ten children with SCID (severe combined
immune deficiency),– helped nine of these patients, but– caused leukemia in three of the patients, and– resulted in one death.
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12.10 CONNECTION: Gene therapy may someday help treat a variety of diseases
▪ The use of gene therapy raises many questions.– How can we build in gene control mechanisms that
make appropriate amounts of the product at the right time and place?
– How can gene insertion be performed without harming other cell functions?
– Will gene therapy lead to efforts to control the genetic makeup of human populations?
– Should we try to eliminate genetic defects in our children and descendants when genetic variety is a necessary ingredient for the survival of a species?
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DNA PROFILING
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12.11 The analysis of genetic markers can produce a DNA profile
▪ DNA profiling is the analysis of DNA fragments to determine whether they come from the same individual. DNA profiling– compares genetic markers from noncoding regions that
show variation between individuals and
– involves amplifying (copying) of markers for analysis.
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Figure 12.11
DNA isisolated.
1
2
3
The DNA ofselectedmarkers isamplified.
The amplifiedDNA iscompared.
Crime scene Suspect 1 Suspect 2
12.12 The PCR method is used to amplify DNA sequences
▪ Polymerase chain reaction (PCR) is a method of amplifying a specific segment of a DNA molecule.
▪ PCR relies upon a pair of primers that are– short, – chemically synthesized, single-stranded DNA
molecules, and– complementary to sequences at each end of the target
sequence.▪ PCR
– is a three-step cycle that– doubles the amount of DNA in each turn of the cycle.
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Figure 12.12
Cycle 1yields two molecules
Cycle 2yields four molecules
DNApolymeraseaddsnucleotides.
Primers bondwith endsof targetsequences.
HeatseparatesDNAstrands.
GenomicDNA
Targetsequenc
e
Primer New DNA
Cycle 3yields eight molecules
3′
5′
5′
3′
3′5′ 5′
5′
5′5′
5′3′ 3′
3′ 3′
5′3′
5′
3′3′5′
5′
321
Figure 12.12_1
Cycle 1yields two molecules
DNApolymeraseaddsnucleotides.
Primers bondwith endsof targetsequences.
HeatseparatesDNAstrands.
GenomicDNA
Targetsequence
Primer New DNA
5′
3′
3′
5′
5′
3′ 3′ 5′
5′
5′ 3′ 5′
5′ 3′
5′3′ 3′
5′
5′3′
5′ 3′321
Figure 12.12_2
Cycle 2yields four molecules
Cycle 3yields eight molecules
▪ The advantages of PCR include– the ability to amplify DNA from a small sample,
– obtaining results rapidly, and
– a reaction that is highly sensitive, copying only the target sequence.
12.12 The PCR method is used to amplify DNA sequences
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12.13 Gel electrophoresis sorts DNA molecules by size
▪ Gel electrophoresis can be used to separate DNA molecules based on size as follows:1. A DNA sample is placed at one end of a porous gel.2. Current is applied and DNA molecules move from the
negative electrode toward the positive electrode.3. Shorter DNA fragments move through the gel matrix
more quickly and travel farther through the gel. 4. DNA fragments appear as bands, visualized through
staining or detecting radioactivity or fluorescence.5. Each band is a collection of DNA molecules of the
same length.
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Figure 12.13
A mixture of DNAfragments ofdifferent sizes
Powersource
Gel
Completedgel
Longer(slower)molecules
Shorter(faster)molecules
Figure 12.13_1
A mixture of DNAfragments ofdifferent sizes
Powersource
Gel
Completedgel
Longer(slower)molecules
Shorter(faster)molecules
Figure 12.13_2
12.14 STR analysis is commonly used for DNA profiling
▪ Repetitive DNA consists of nucleotide sequences that are present in multiple copies in the genome.
▪ Short tandem repeats (STRs) are short nucleotide sequences that are repeated in tandem,– composed of different numbers of repeating units in
individuals and– used in DNA profiling.
▪ STR analysis– compares the lengths of STR sequences at specific sites
in the genome and– typically analyzes 13 different STR sites.
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Figure 12.14A
Crime sceneDNA
Suspect’sDNA
STR site 1 STR site 2
The number of shorttandem repeats match
The number of short tandemrepeats do not match
Figure 12.14B
CrimesceneDNA
Suspect’sDNA
Longer STR fragments
Shorter STR fragments
12.15 CONNECTION: DNA profiling has provided evidence in many forensic investigations
▪ DNA profiling is used to– determine guilt or innocence in a crime,
– settle questions of paternity,
– identify victims of accidents, and
– probe the origin of nonhuman materials.
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Figure 12.15B
Cheddar Man and one of his modern-day descendants
12.16 RFLPs can be used to detect differences in DNA sequences
▪ A single nucleotide polymorphism (SNP) is a variation at a single base pair within a genome.
▪ Restriction fragment length polymorphism (RFLP) is a change in the length of restriction fragments due to a SNP that alters a restriction site.
▪ RFLP analysis involves– producing DNA fragments by restriction enzymes and
– sorting these fragments by gel electrophoresis.
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Figure 12.16Restrictionenzymes
addedDNA sample
1DNA sample
2
CutCut
Cut
w
x
y y
z
Sample1
Sample2
z
x
wy y
Longerfragments
Shorterfragments
Figure 12.16_1
Restrictionenzymes
addedDNA sample 1 DNA sample
2w
x
y y
z
Cut
Cut Cut
Figure 12.16_2
Sample1
z
x
wy y
Longerfragments
Shorterfragments
Sample2
GENOMICS
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12.17 Genomics is the scientific study of whole genomes
▪ Genomics is the study of an organism’s complete set of genes and their interactions.
– Initial studies focused on prokaryotic genomes.
– Many eukaryotic genomes have since been investigated.
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Table 12.17
12.17 Genomics is the scientific study of whole genomes
▪ Genomics allows another way to examine evolutionary relationships.– Genomic studies showed a 96% similarity in DNA
sequences between chimpanzees and humans.
– Functions of human disease-causing genes have been determined by comparing human genes to similar genes in yeast.
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12.18 CONNECTION: The Human Genome Project revealed that most of the human genome does not consist of genes
▪ The goals of the Human Genome Project (HGP) included– determining the nucleotide sequence of all DNA in the
human genome and
– identifying the location and sequence of every human gene.
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12.18 CONNECTION: The Human Genome Project revealed that most of the human genome does not consist of genes
▪ Results of the Human Genome Project indicate that– humans have about 20,000 genes in 3.2 billion
nucleotide pairs,– only 1.5% of the DNA codes for proteins, tRNAs, or
rRNAs, and– the remaining 98.5% of the DNA is noncoding DNA
including– telomeres, stretches of noncoding DNA at the ends of
chromosomes, and– transposable elements, DNA segments that can move or be
copied from one location to another within or between chromosomes.
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Figure 12.18Exons (regions of genes coding for protein
or giving rise to rRNA or tRNA) (1.5%)
RepetitiveDNA thatincludestransposableelementsand relatedsequences(44%)
Introns andregulatorysequences(24%)
UniquenoncodingDNA (15%)
RepetitiveDNAunrelated totransposableelements(15%)
12.19 The whole-genome shotgun method of sequencing a genome can provide a wealth of data quickly
▪ The Human Genome Project proceeded through three stages that provided progressively more detailed views of the human genome.1. A low-resolution linkage map was developed using
RFLP analysis of 5,000 genetic markers.
2. A physical map was constructed from nucleotide distances between the linkage-map markers.
3. DNA sequences for the mapped fragments were determined.
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12.19 The whole-genome shotgun method of sequencing a genome can provide a wealth of data quickly
▪ The whole-genome shotgun method– was proposed in 1992 by molecular biologist J. Craig
Venter, who
– used restriction enzymes to produce fragments that were cloned and sequenced in just one stage and
– ran high-performance computer analyses to assemble the sequence by aligning overlapping regions.
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12.19 The whole-genome shotgun method of sequencing a genome can provide a wealth of data quickly
▪ Today, this whole-genome shotgun approach is the method of choice for genomic researchers because it is– relatively fast and– inexpensive.
▪ However, limitations of the whole-genome shotgun method suggest that a hybrid approach using genome shotgunning and physical maps may prove to be the most useful.
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Figure 12.19
ChromosomeChop up each chromosomewith restriction enzymes
Sequence the fragments
DNA fragments
Align the fragments
Reassemble the fullsequence
12.20 Proteomics is the scientific study of the full set of proteins encoded by a genome
▪ Proteomics– is the study of the full protein sets encoded by
genomes and
– investigates protein functions and interactions.
▪ The human proteome includes about 100,000 proteins.
▪ Genomics and proteomics are helping biologists study life from an increasingly holistic approach.
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12.21 EVOLUTION CONNECTION: Genomes hold clues to human evolution
▪ Human and chimp genomes differ by– 1.2% in single-base substitutions and– 2.7% in insertions and deletions of larger DNA
sequences.
▪ Genes showing rapid evolution in humans include– genes for defense against malaria and tuberculosis,– a gene regulating brain size, and– the FOXP2 gene involved with speech and vocalization.
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12.21 EVOLUTION CONNECTION: Genomes hold clues to human evolution
▪ Neanderthals– were close human relatives,– were a separate species,– also had the FOXP2 gene,– may have had pale skin and red hair, and– were lactose intolerant.
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Figure 12.21
Reconstruction of a Neanderthal female, based on a 36,000 year old skull
1. Explain how plasmids are used in gene cloning.
2. Explain how restriction enzymes are used to “cut and paste” DNA into plasmids.
3. Explain how plasmids, phages, and BACs are used to construct genomic libraries.
4. Explain how a cDNA library is constructed and how it is different from genomic libraries constructed using plasmids or phages.
5. Explain how a nucleic acid probe can be used to identify a specific gene.
You should now be able to
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6. Explain how different organisms are used to mass-produce proteins of human interest.
7. Explain how DNA technology has helped to produce insulin, growth hormone, and vaccines.
8. Explain how genetically modified (GM) organisms are transforming agriculture.
9. Describe the risks posed by the creation and culturing of GM organisms and the safeguards that have been developed to minimize these risks.
You should now be able to
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10. Describe the benefits and risks of gene therapy in humans. Discuss the ethical issues that these techniques present.
11. Describe the basic steps of DNA profiling.
12. Explain how PCR is used to amplify DNA sequences.
13. Explain how gel electrophoresis is used to sort DNA and proteins.
14. Explain how short tandem repeats are used in DNA profiling.
You should now be able to
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15. Describe the diverse applications of DNA profiling.
16. Explain how restriction fragment analysis is used to detect differences in DNA sequences.
17. Explain why it is important to sequence the genomes of humans and other organisms.
18. Describe the structure and possible functions of the noncoding sections of the human genome.
19. Explain how the human genome was mapped.
You should now be able to
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21. Compare the fields of genomics and proteomics.
22. Describe the significance of genomics to the study of evolutionary relationships and our understanding of the special characteristics of humans.
You should now be able to
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