Transcript Living World Notes

13-1: Changing the Living World
Biology 2
Introduction
• Have you ever seen a dog
show?
• Breeds are a result of genetic
variation
Selective
Breeding
• Human created different
breeds to do different jobs
• SELECTIVE BREEDING: method of
breeding that allows only
those individual organisms
with desired characteristics to
produce the next generation
– By choosing which breeds we
want to use, we can create
different breeds
Selective
Breeding
• Human created different breeds
of dogs to do different jobs
• Humans use selective breeding to
take advantage of natural genetic
variations
• Almost all domestic animals are
produces by selective breeding
– Horses, cats, farm animals, and
plants
Selective
Breeding
• HYBRIDIZATION: breeding
technique that involves crossing
dissimilar individuals to bring
together the best traits of both
organisms
• Some plants can be created by
crossing 2 different “types” of
parents
– For example: crossing a diseaseresistant parent with a fastgrowing parent gives offspring
plants both traits
Selective
Breeding
• To help maintain traits, some
breeders use inbreeding
• INBREEDING: continued breeding
of individuals with similar
characteristics to maintain the
desired characteristics of a line of
organisms
• Inbreeding helps to make sure
that traits for specific species are
maintained
– Can cause genetic defects such as:
blindness, joint problems, etc…
Increasing
Variation
• Selective breeding is near
impossible without variations
• Breeders can increase
variations by causing
mutations
• With the right items
(radiation/chemicals)
breeders can produce mutants
with good mutations
– Some may not be found in the
normal population
Increasing
Variation
• Causing mutations has been
useful with bacteria
– Increases chances of producing a
useful mutation
• Have been able to develop
hundreds of useful bacteria!
• Some mutant bacteria can
digest oil
• These bacteria have been
used in oil spills
Increasing
Variation
• Drugs that prevent
chromosome separation
during meiosis have been
useful in plant breeding
• Sometimes produce plants
that have 2x or 3x normal
chromosome numbers
– Called Polyploidy (extra
chromosomes)
• Can produce bigger stronger
plants than normal plants
– Bananas and Citrus!