Selective Breeding: Techniques and Applications

1. Chapter 15: Genetic Engineering Section 15-1: Selective Breeding

2. Selective Breeding • When humans allow only organisms with “wanted” or “desired” characteristics to produce the next generation • Technique used for thousands of years to produce new varieties of cultivated plants and domesticated animals • Two methods: hybridization and inbreeding

3. Hybridization • Crossing dissimilar individuals to bring together the best characteristics of both organisms • Hybrids often hardier than either parent • Example: crossing a disease resistant plant with one that produces a lot of food

4. Inbreeding • Continued breeding of individuals with similar characteristics • Maintains desirable characteristics in a line of organisms • Example: pure bred dogs and cats • Can be risky – higher chance of recessive alleles pairing, genetic defects

5. Increasing Variation • Scientists who manipulate organisms’ genetic makeup are using biotechnology – the application of a technological process , invention, or method to living organisms • Types of biotechnology include selective breeding, increasing mutation rates, using drugs to create polyploid plants, and others

6. Bacterial Mutations • Using radiation or chemicals (mutagens) can increase the rate of mutation • Breeders can create mutants with beneficial characteristics • Example: oil digesting mutant bacterial strains are used to help clean up oil spills; working on bacteria that can clean up radioactive substances or metal pollution

7. Polyploid Plants • Drugs that prevent chromosome separation in meiosis are useful in plant breeding, to create polyploid plants that are larger and stronger than the normal diploids • Many important crop plants are polyploid