Unit 4 Genetics

1. Unit 4 Genetics Ch. 13 Genetic Engineering

2. Selective Breeding • Selective breeding - allowing animals with desired characteristics to reproduce • It takes advantage of naturally occurring genetic variation in plants, animals, etc.

3. Selective Breeding • Humans use selective breeding to pass desired traits on to the next generation of organisms • Nearly all domestic animals (horses, cats, etc.) & most crop plants have been produced by selective breeding

4. Selective Breeding • Hybridization - crossing dissimilar individuals to bring together the best of both organisms • The organisms produced, hybrids, are usually hardier than both parents

5. Selective Breeding • Inbreeding - continued breeding of individuals with similar characteristics • Many breeds of dogs are maintained by inbreeding • It helps to ensure the characteristics of each breed are preserved

6. Increasing Variation • Selective breeding can increase genetic variation in a population by causing mutations to occur • SB was used to create oil-eating bacteria, used to clean up oil spills

7. Manipulating DNA • Scientists study & change DNA molecules • Different techniques are used to extract (remove) DNA from cells, to cut DNA into smaller pieces, to identify the sequence of bases in a DNA molecule, & to make unlimited copies of DNA

8. The Tools of Molecular Biology • Genetic engineering - making changes in the DNA code of a living organism

9. The Tools of Molecular Biology • Cutting DNA: • DNA molecules are too large to be analyzed, so biologists cut them precisely into smaller fragments • Restriction enzymes - enzymes that cut DNA at a specific sequence of nucleotides

10. The Tools of Molecular Biology • Separating DNA: • Gel electrophoresis - a mixture of DNA fragments is placed at 1 end of a gel, & an electric voltage is applied to the gel • When the power is turned on, DNA fragments move toward the + end of the gel • Smaller DNA fragments move faster & farther

11. Gel Electrophoresis

12. Using the DNA Sequence • Cutting & pasting: • DNA sequences can be changed • Restriction enzymes - used to take a gene from 1 organism & attach it to the DNA of another organism • Recombinant DNA - DNA molecules produced by combining DNA from different sources

13. Using the DNA Sequence • Making copies: • Polymerase chain reaction (PCR) - technique that allows biologists to make many copies of a particular gene

14. Cell Transformation • During transformation, a cell takes in DNA from the outside (DNA from another organism) • That external DNA combines with the cell’s DNA • As the cell copies its own DNA, it also copies the external DNA, since the 2 were combined during transformation

15. Transforming Bacteria • Plasmid - circular DNA of bacteria

16. Applications of Genetic Engineering • Genetic engineering makes it possible to transfer DNA sequences, including whole genes, from 1 organism to another • It has spurred the growth of biotechnology, a new industry that is changing the way we interact with the living world

17. Transgenic Organisms • Transgenic - organisms have genes from other species • A gene from 1 organism can be inserted into cells from another organism • Those transformed cells can be used to grow new organisms

18. Transgenic Organisms • Transgenic Animals: • They have been used to study genes & improve the food supply • Mice have been produced with human genes that make their immune systems similar to ours • Livestock have extra copies of human growth hormone

19. Transgenic Organisms • Transgenic Plants: • Many crop plants contain genes that produce a natural insecticide • Others have genes that allow them to resist weed-killing chemicals • Rice has been genetically modified to contain Vitamin A, essential for human health

20. Cloning • Clone - a member of a population of genetically identical cells produced from a single cell

21. Cloning