Chapter 13 Genetic Engineering

1. Chapter 13 Genetic Engineering Changing the Living World

2. Selective Breeding • Humans use selective breeding, which takes advantage of naturally occurring genetic variations. • Domestic animals • Farm animals • Crop plants • Pass desired traits to the next generation

3. Hybredization • Luther Burbank may have been the greatest selective breeder of all time (1849 – 1926) • Used Hybredization crossing dissimilar individuals to bring out the best in each • Combined the disease resistance of one plant with the food-producing capacity of another • The result was a new line of plants that allowed farmers to increase food production

4. Inbreeding • The continued breeding of individuals with similar characteristics • Breeds of dogs such as beagles and poodles • Risks • Chance that two recessive alleles form a genetic defect • Joint problems with German shepherds for example

5. Increasing Variation • Selective breeding is possible because of the wide variation found in natural populations • Breeders increase the variation by inducing mutations (mutations are the cause of variations) • With luck over a number of attempts desirable traits may be found.

6. Increasing Variation 2 • Because of the small size of bacteria, radiation or chemical treatment may produce some of the bacteria with useful characteristics. • Bacteria that digest oil • Bacteria that produce hydrogen

7. Increasing Variation 3 • Producing new kinds of plants • Prevent chromosomal separation • Sometimes produce cells that have two to three times the number of chromosomes • Called polyploidy the extra chromosomes in plants sometimes make them larger and stronger. • Polyploidy is fatal in animals

8. Manipulating DNA • Scientists have broken the DNA code • They study the structure of DNA and its chemical properties. • Techniques are used to extract DNA from cells and cut it into smaller pieces and identify the sequence of bases in a DNA molecule and make unlimited copies.

9. Manipulating DNA • Tools • DNA extraction – chemicals can separate the DNA from other cell parts. • Cutting DNA – Restriction enzymes are known and each one cuts DNA at a specific sequence of nucleotides.

11. DNA fragments can be separated using gel electrophoresis. A DNA fragment is placed at one end of a porous gel, and voltage applied. DNA molecules, which are negatively charged move to the positive end of he gel. • The sequence can then be read.

12. Applications of Genetic Engineering • Transgenic Organisms – It is possible to construct organisms that are transgenic, meaning that they contain genes from other species. The transformed cells grow new organisms. • Transgenic microorganisms – transgenic bacteria now produce substances that form proteins cheaply and in great quantities. • ie. Insulin, growth hormone, and clotting factor

13. Cloning • A clone is a member of a population of genetically identical cells produced from a single cell.