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

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

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

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

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

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

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