Transcript Chapter 15: Genetic Engineering

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