
Studying and Manipulating Genomes Chapter 11
Genetic Engineering • Genes are isolated, modified, and inserted into an organism • Same or different organism • Made possible by Recombinant DNA technology • Cut up DNA and recombine pieces
Molecular Toolkit • 1. Get DNA and recombine it • Restriction enzymes • 2. Copy it • Cloning • PCR • 3. Analyze it • Sequencing • Molecular Fingerprinting
Using Plasmids • Plasmid: a small circle of bacterial DNA • Foreign DNA inserted into plasmid • Plasmid delivers DNA into another cell
Polymerase Chain Reaction (PCR) • Used to Amplify a specific region of DNA. • Requires: • DNA as template • DNA polymerase • Cycles of heating and cooling
DNA Fingerprinting • Tandem Repeats • Short regions of DNA that differ substantially among people • Many sites in genome where tandem repeats occur • Each person carries a unique combination of repeats
Analyzing DNA Fingerprints • DNA is cut and then separated based on size of the DNA • “Stained” and pattern of sizes is viewed • Identify or rule out criminal suspects • Identify bodies • Determine paternity
Transgenic Plants • Transgenic means? • Use bacterial cloning vectors to insert foreign gene (Ti plasmid) plant cell foreign gene in plasmid
Transgenic Plants Resistant to herbicides Insect resistance
“Frankenfood” • Genetically engineered foods are widespread in the US • Cut costs, reduce herbicide and pesticide use, enhance yields • What effect will they have on humans?
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
How to keep the plants under control or make a HUGE profit? • Terminator gene • Seeds from transgenic plants will be sterile • Traitor gene • Seeds from transgenic plants require yearly application of chemical to turn them “on” again
Genetically Engineered Bacteria • Produce medically valuable proteins • INSULIN!!!! • Breakdown environmental contaminants • Designed to survive only under narrow conditions
Transgenic Animals • Early experiments in mice • Injection of human growth-hormone gene produced giant mice • “Knockout mice” • Study defective gene in mice instead of humans • Effects of transgenic animals seen in agriculture, medicine, and industry.
Transgenic Animals • Agriculture • Breeding and Quality – cows with more milk, sheep with more wool, pig/cattle with more meat • Industry • Goats that make spider silk • Medicine • Goats – antithrombin • Rabbits – IL-2 for immune system • Cattle – collagen for skin grafts
Xenotransplantation • Human organs are in short supply • Pig organs are similar, but human body rejects them as foreign • Knockout pig genes that trigger rejection • Can interspecies transplants introduce new diseases to humans?
The Human Genome Project • Sequence all the bases in human DNA (3 billion!) • Finished in 2003 • 20,000 genes • Now what?
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
Viruses and Gene Therapy • Retroviruses Contain RNA that is injected into host cell along with enzymes. • Reverse Transcriptase converts the RNA to DNA. • Integrase inserts the DNA into the host genome Adenoviruses Contains DNA that is put in the host nucleus and transcribed.
Gene Therapy For SCID-X1 • Designed to cure “bubble babies” • Immune system can’t fight infection
Who Gets Enhanced? • Eugenic engineering • Selecting for “desirable” human traits • Creation of “designer” babies • Who should decide what genetic traits can or should be altered?