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Studying and Manipulating Genomes
Chapter 11
Golden Riceor Frankenfood?
• Scientists transferred daffodil genes into rice
• Rice with beta-carotene may help prevent vitamin A deficiencies
• Opponents fear unforeseen consequences of creating genetically modified organisms
Genetic Changes
• Humans have changed the genetics of other species for thousands of years– Artificial selection of plants and animals
• Natural processes also at work– Mutation, crossing over
Genetic Engineering
• Genes are isolated, modified, and inserted into an organism
• Made possible by recombinant DNA technology
– Cut up DNA and recombine pieces
– Amplify modified pieces
Specific Cuts
• Restriction enzymes cut DNA at a specific nucleotide sequence
• Cuts leave “sticky ends” on DNA fragments that pair with matching cuts
Making Recombinant DNA
5’
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C T T A A
A A T T C
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G A A T T C
C T T A A G3’
5’
one DNA fragment another DNA fragment
3’
5’
Making Recombinant DNA
nick
5’
3’
3’
5’
G A A T T C
C T T A A G
nick
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DNA ligase action
DNA Fingerprints
• Unique array of DNA fragments
• Inherited from parents in Mendelian
fashion
• Even full siblings can be distinguished
from one another by this technique
Analyzing DNA Fingerprints
• DNA is separated by gel electrophoresis
• Pattern of bands is used to
– Identify or rule out criminal suspects
– Identify bodies
– Determine paternity
A DNA Fingerprint
DNA Sequence Data
• Evolutionary trends
• Potential therapies for genetic diseases
• Data bases using computer technology
Computers and Gene Sequencing
The Human Genome Project
Map the entire human genome
Sequencing completed in
2003
Genomics
• Structural genomics: mapping and sequencing genomes of individuals
• Comparative genomics: possible evolutionary relationships of groups of organisms
Human Gene Therapy
• Even with the human genome fully sequenced, it is still not easy to manipulate
• Viruses used to insert genes into cultured human cells
• Very difficult to get modified genes to work where and how they should
Transgenic Plants
• Contain DNA from another species
• New genes make crop plants less vulnerable to disease and pests
• Use bacterial cloning vectors to insert foreign gene (Ti plasmid)
Transgenic Cotton
• Resistant to herbicides
• Insecticide gene
Genetically Engineered Bacteria
• Produce medically valuable proteins
• Breakdown environmental contaminants
• Designed to survive only under narrow
conditions
Transgenic Animals
• Early experiments in mice– Injection of rat gene corrected a growth-
hormone deficiency – Injection of human growth-hormone gene
produced giant mice
• Human genes are now routinely transferred into animals to produce human proteins for use as drugs
Transgenic Mouse
• With genes for fluorescent protein