Studying and Manipulating Genomes Chapter 11

Golden Rice or 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’ 3’ G C T T A A A A T T C G G C T T A AG 3’ 5’ one DNA fragmentanother DNA fragment 3’ 5’

Making Recombinant DNA nick 5’ 3’ 5’ GA A T T C C T T A AG nick GA A T T C C T T A AG 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