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Studying and Manipulating Genomes

Studying and Manipulating Genomes

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Studying and Manipulating Genomes

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  1. Studying and Manipulating Genomes Chapter 11

  2. 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

  3. Molecular Toolkit • 1. Get DNA and recombine it • Restriction enzymes • 2. Copy it • Cloning • PCR • 3. Analyze it • Sequencing • Molecular Fingerprinting

  4. Making Recombinant DNA

  5. Using Plasmids • Plasmid: a small circle of bacterial DNA • Foreign DNA inserted into plasmid • Plasmid delivers DNA into another cell

  6. Polymerase Chain Reaction (PCR) • Used to Amplify a specific region of DNA. • Requires: • DNA as template • DNA polymerase • Cycles of heating and cooling

  7. 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

  8. 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

  9. Transgenic Plants • Transgenic means? • Use bacterial cloning vectors to insert foreign gene (Ti plasmid) plant cell foreign gene in plasmid

  10. Transgenic Plants Resistant to herbicides Insect resistance

  11. Transgenic Plants for Biofuels

  12. “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?

  13. 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

  14. 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

  15. Genetically Engineered Bacteria • Produce medically valuable proteins • INSULIN!!!! • Breakdown environmental contaminants • Designed to survive only under narrow conditions

  16. 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.

  17. 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

  18. 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?

  19. The Human Genome Project • Sequence all the bases in human DNA (3 billion!) • Finished in 2003 • 20,000 genes • Now what?

  20. 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

  21. 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.

  22. Gene Therapy For SCID-X1 • Designed to cure “bubble babies” • Immune system can’t fight infection

  23. 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?