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

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A A T T C

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one DNA fragment another DNA fragment

3’

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Making Recombinant DNA

nick

5’

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G A A T T C

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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