Advances in Genetics

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Advances in Genetics
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Methods of Developing Organisms With Desirable
Traits

• Selective Breeding
• Cloning
• Genetic Engineering

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Selective Breeding

• The process of selecting a few organisms with
  desirable traits to serve as parents of the next
  generation.
• Used for thousands of years with various plants
  and animals.
• Types
• Inbreeding
• Hybridization

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Inbreeding

• Two individuals that have identical or similar
  sets of alleles are crossed.
• Resulting organisms are very similar to their
  parents.
• Used to produce breeds of animals with specific
  traits
• Ex. Purebred Lab retrievers, German shepherds
• Increases probability that organisms may inherit
  alleles that lead to genetic disorders.
• Ex. Hip problems in many breeds of dogs

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Hybridization

• Two genetically different individuals are crossed
• Organism is bred to have the best traits from
  both parents
• Ex. Corn with many kernels crossed with
  disease-resistant corn
• Most crops grown on farms and in gardens are
  hybrids.

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Cloning

• Although selective breeding does not allow the
  breeder to control whether the desired allele
  will be passed or not, cloning does.
• Clone
• Organism that is genetically identical to the
  organism from which it was produced.
• Cloning Plants
• Small part is cut from plant and regrows into a
  genetically identical plant.

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Cloning in Plants
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Cloning Animals

• Dolly the Sheep
• Removed egg cell from one sheep
• Nucleus in egg cell replaced with nucleus from a
  six-year old sheep
• Egg implanted into uterus of 3rd sheep
• Dolly born 5 months later, genetically identical
  to the six-year old sheep

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Genetic Engineering

• Genes from one organism are transferred into the
  DNA of another organism.
• Called Gene Splicing
• DNA molecule cut open
• Gene from another organism is spliced into it
• Used to
• Produce medicine
• Improve food crops
• Try to cure human genetic disorders

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Genetic Engineering in Bacteria

• Bacteria used because they reproduce rapidly.
• Insulin gene spliced into bacteria- (into the
  plasmid)- so that the bacteria will produce
  insulin.

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Genetic Engineering in Bacteria
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Genetic Engineering in Other Organisms

• Used in plants and other animals.
• Ex. Human clotting gene inserted into cows.
  Cows then produce clotting protein in milk, which
  can then be extracted for humans.
• Gene Therapy
• Working copies of a gene inserted directly into
  cells of a person with a genetic disorder
• Used to correct some genetic disorders

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Genetic Engineering
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DNA Fingerprinting

• DNA pattern is unique for each individual
• Used often in crime investigations

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Human Genome Project

• Identified the DNA sequence of every gene in the
  human genome.
• Involves nearly 25,000 genes
• May lead to new treatments and prevention
  strategies for many genetic disorders and for
  diseases such as cancer.

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Summary Questions

• Name three techniques that people have used to
  produce organisms with desired traits.
• Why do scientists want to identify the DNA
  sequence of every human gene?
• What is genetic engineering? Describe three
  possible benefits of this technique.
• Explain how a DNA fingerprint is produced. What
  information can a DNA fingerprint reveal?