Genetic Engineering

1. Genetic Engineering Selective Breeding & Increasing Variation

2. Selective Breeding • HUMANS cross parents with desired traits offspring with desired traits (flower color, disease resistance, increased milk production) • Dogs and cats, farm animals, crop plants

3. Selective Breeding Hybridization Inbreeding Maintain desired traits Cross similar individuals Genetically similar individuals breeding increase chance for two recessive alleles Defects can result; ex dogs—blindness, leg deformity, blue Fugates of KY • Cross dissimilar individuals best of both • Ex. Disease resistance with food producing capacity • Dogs?

4. Increasing Variation • Breeders use mutagens to cause mutations • ultimate source of genetic variation • Some mutations unique and desirable • Ex: chemicals and radiationoil-eating bacteria! • Polyploidy in plants—larger, stronger than 2n

5. Manipulating DNA • Change DNA! • extract • cut • identify gene sequences • make unlimited copies • recombine

6. DNA extraction—chemical (ex. strawberry) • Cut—restriction enzymes cut DNA at specific sequences (chemical scissors) • Fragments • Plasmids (circular DNA in bacteria)

7. Different restriction enzymes cut DNA in different ways. • each enzyme has a different restriction site (lock and key)

8. Restriction Sites • some cut straight across and leave “blunt ends” • some make staggered cuts and leave “sticky ends”

9. Gel electrophoresis • Separates DNA fragments by size: • DNA sample is cut with restriction enzymes • Electrical current pulls DNA fragments through gel (“JELLO swimming”) • Smaller fragments move faster, travel farther than larger fragments • Fragments of different sizes appear as bands on the gel

10. DNA Fingerprinting DNA fingerprints identify people at the molecular level. • evidence in criminal cases • paternity tests • studying biodiversity • tracking genetically modified crops

11. DNA fingerprinting depends on the probability of a match. • Many people have thesame number ofrepeats in a certainregion of DNA. • The probability that two people share identicalnumbers of repeats inseveral locations isvery small. (mother) (child 1) (child 2) (father)

12. The Crime On the evening of November 1, at approximately 8:15 p.m., Jimmy Sweet entered his bedroom, walked over to his desk, and sat down at his computer. While reaching for the computer's switch he noticed, out of the corner of his eye, that one of the items on a typically well-organized shelf was out of place. Jimmy shot across the room for a closer examination. Sure enough, the object in question had indeed been disturbed. The object had been sealed in an air-tight package. The package was now ripped open. The object was still inside, but it was no longer in its original condition. In Jimmy's eyes, it was now worthless. Jimmy pulled out what had been his most-valued possession -- his lollipop. The confectionery treat was now a sticky mess. Someone had obviously indulged him- or herself in its sugary molecules.

13. Create the FingerprintAnalyze the FingerprintChoose the Culprit • http://www.pbs.org/wgbh/nova/sheppard/analyze.html

14. (bacterial DNA) Cell Transformation • Organism’s DNA can be changednew traits • New genes can be added • Recombinant DNAgenes from more than one organism.

15. Bacterial plasmids used to make recombinant DNA. • plasmids are loops of DNA in bacteria • restriction enzymes cut plasmid and foreign DNA • foreign gene inserted into plasmid

16. Transgenic organism--one or more genes from another organism inserted into its genome and TURNED ON (expressed)

17. Transgenic bacteria produce human proteins: • Human gene spliced into bacteria DNA • Bacteria express the gene • Insulin, human growth hormone • Transgenic plants are common in agriculture: • Transgenic bacteria infect a plant and plant expresses gene • Many crops now genetically modified (GM) • Produce own insecticide, Fertilizer, resist freezing • Luciferase tobacco???

18. Transgenic animals are used to study diseases and gene functions: • Human immune system and HIV in mice • Hardier livestock

19. Concerns about uses of genetic engineering: • possible long-term health effects of eating GM foods • possible effects of GM plants on ecosystems and biodiversity

20. Clone --genetically identical copy of a gene or organism. • Dolly 1997 (Ian Wilmut)

21. Cloning in nature (asexual reproduction) • bacteria (binary fission) • plants (strawberries—vegetative propagation) • simple animals (budding, regeneration)

22. Mammals cloned via nuclear transfer: • nucleus (n) is removed from an egg cell • nucleus (2n) of a cell from the animal to be cloned is implanted in the egg

23. Cloning potential benefits: • Organs for transplant into humans • Save endangered species • Cloning concerns: • Low success rate • Clones “imperfect” and less healthy than original animal • telomeres • Decreased biodiversity

24. What does it mean for Homo sapiens? • Human Genome Project—sequence and analyze entire human DNA sequence • Locate and identify specific genes • GeneTherapy—potential to replace absent or faulty genes with normal working genes • Imagine: What will a biology classroom or doctor visit look like in 30 years?