CHAPTER 13 Genetic Engineering

1. CHAPTER 13Genetic Engineering

2. 13-1 Changing the Living World Selective Breeding- allowing only those animals with desired characteristics to produce the next generation ex: different dog breeds

3. Selective Breeding • Selective breeding uses genetic variation in organisms to pass desired traits onto the next generation. Luther Burbank (1849-1926) • Created 800 varieties of plants • Disease resistant Burbank potato- which was used in Ireland to fight potato blight

4. Hybridization • Hybridization- crossing dissimilar individuals to bring together the best of both organisms • Hybrids are often stronger than either parent • Ex: crossing disease resistance with food producing capacity

5. Inbreeding • Inbreeding- continued breeding of individuals with desired characteristics • Used to maintain desired characteristics of a line • Problems: greater chance of having two recessive alleles for a genetic defect. • Ex: dog breeds that have joint problems and blindness

6. Increasing Variation • Breeders can increase the genetic variation in a population by inducing mutations • Example: creating bacteria that can digest oil and clean up an oil spill • Polyploid plants- are usually stronger and larger

7. 13-2 Manipulating DNA The tools of molecular biology Genetic engineering- making changes to the DNA of an organism What is possible with genetic engineering? Are there any ethical or moral considerations?

8. DNA extraction- cells are lysed (broken) and the DNA is separated from the other cell parts • Cutting DNA- restriction enzymes will cut DNA at a certain location • Restriction enzymes comes from bacteria that use them to protect against foreign DNA

9. Restriction Enzymes create sticky ends (ends of a DNA that can bind to other DNA fragments)

10. Separating DNA- done by Electrophoresis • Electrophoresis- separating DNA fragments based on size by using electricity

11. DNA is slightly negative- it will travel to a positive charge • DNA is cut into small fragments • The DNA goes through a matrix (agarose or acrylamide) • The smaller fragments travel faster • Ethidium bromide can be added to see the DNA fragments with UV light

16. Using the DNA sequence Reading the DNA sequence (DNA sequencing) DNA is put into a tube with DNA polymerase Nucleotides are added to the tube Some of the nucleotides have a tag. If these nucleotides are added to DNA then it stops replicating. The tag can be radioactive or a florescent dye.

18. Recombinant DNA- combining DNA from different sources • Two different organisms • Natural DNA with artificially created DNA

19. PCR Polymerase Chain Reaction • PCR- process of copying a certain segment of DNA. The segment is copied many times. • Taq polymerase- copies DNA, does not denature at high temperatures • Primer- short segment of DNA used to begin replication • Developed by Kary Mullis

25. 13-3 Cell Transformation • Transformation- a cell takes in foreign DNA. This DNA is expressed (transcribed and translated) by the cell. Plasmid- small, circular segment of DNA Plasmids are useful in transformation.

30. Transformation • Genetic marker- something that distinguishes organisms with a certain DNA • Antibiotic resistance is a common genetic marker

31. Transforming plant cells • A bacteria can infect a plant and transfer its DNA to the plant cells. • 1. A certain gene is put into a plasmid. • 2. The bacteria is transformed to accept the plasmid. • 3. The bacteria infects the plant. • 4. The plant now has the inserted gene and incorporates it into its chromosomes.

33. Transforming animal cells • Animal cells can be transformed • 1. Inject DNA directly into an egg • 2. Use a vector (virus) to transfer DNA into a cell

34. 13-4 Applications of Genetic Engineering • Luciferase- enzyme that allows fireflies to glow • Luciferase gene was inserted into a plant • The plant glowed

35. Transgenic Organisms • Transgenic- organisms that have genes from other species • Transgenic bacteria- produce human insulin, growth hormone, and clotting factor • Advantages: bacteria reproduce quickly and are easy to grow

36. Transgenic animals • Mice are given human genes for their immune system to study the effect of various diseases • Livestock are given extra copies of growth genes to grow faster • Some animals are given genes to produce certain human proteins. • Organ donation?

37. Transgenic plants • In 2000, 52% of soy and 25% of corn grown in the US was genetically modified (GM) • Modified to produce an insecticide and resist weed-killing chemicals • Other possible modifications: rice with extra Vitamin A

38. Should we genetically modify our plants and animals? • What are the risks or rewards?

39. Cloning • Clone- an exact genetic copy of another organism • Do clones exist naturally?

40. Is cloning useful? • Why would you want to clone an animal?

41. 1997, Ian Wilmut cloned a sheep, “Dolly” • Cows, pigs, mice and other mammals have also been cloned

42. 1. Cells taken from donor • 2. An egg from a second donor has its nucleus removed • 3. DNA from first donor is inserted into the egg of the second donor • 4. The egg is grown and inserted into a surrogate mother • 5. Clone is born