GENETIC ENGINEERING

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GENETIC ENGINEERING

• Chapter 13

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Selective Breeding

• Humans use selective breeding to pass desired
  traits on to the next generation of organisms.
• Allows only those animals with desired
  characteristics to produce the next generation.
• 2 Types of Selective breeding
• Hybridization
• Inbreeding

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Hybridization

• Hybridization cross breeding non-similar
  individuals that bring together the best traits
  of both organisms.
• Produces hybrids (mixed organisms) that are often
  BETTER than either parent
• disease resistant plants
• plants with higher food producing capacity

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Inbreeding

• Inbreeding - continued breeding of individuals
  with similar characteristics
• Used to maintain the desired characteristic of
  an organism.
• Ex? Dog breeding (beagles, poodles, golden
  retrievers, etc.)
• Risks of inbreeding
• genetically similar breeds increase the
  likelihood of passing on recessive alleles for
  genetic defects

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Increasing Variation

• Breeders can increase the genetic variation in a
  population by causing mutations, which are the
  ultimate source of genetic variability.
• mutations are inheritable changes in DNA that
  occur spontaneously
• radiation or chemicals may be used
• If lucky, breeders can produce a few mutants with
  desirable characteristics that are not found in
  the original population

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Manipulating/ Changing DNA

• Genetic engineering is used to make changes in
  the DNA.
• First, the DNA is extracted/removed from a cell
• Restriction enzymes are then used to cut the DNA
  at a specific location.
• The fragments are then separated and analyzed
  using gel electrophoresis (used to compare genes
  of different organisms) ? this way scientists can
  locate identify single genes out of millions in
  a genome.

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Cutting DNA with Restriction Enzymes
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Separating DNA with Gel Electrophoresis
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DNA Sequencing

• In DNA sequencing, a complementary DNA strand is
  made using a small proportion of fluorescently
  labeled nucleotides.

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Cutting, Pasting, Making Copies of DNA

• Recombinant DNA is produced by combining DNA from
  different sources.
• These DNA sequences are joined by using enzymes
  to splice/join the DNA together
• A polymerase chain reaction (PCR) allows
  biologists to make many copies of a particular
  gene
• A few dozen cycles of PCR can produce millions of
  copies of a DNA sequence

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During cell transformation, a cell incorporates/
includes foreign DNA into its own DNA. A plasmid
(circular DNA) is made, and contains a genetic
marker, which distinguishes the human DNA from
the bacterial DNA. One way to make recombinant
DNA is to insert a human gene into bacterial DNA.
The new combination of genes is then returned to
a bacterial cell, and the bacteria can produce
the human protein.
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Knock-Out Genes

• Recombinant DNA can replace a gene in an animals
  genome. When recombinant DNA is inserted into
  the target location, the host cells original
  gene is lost or knocked out of its place.

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Applications of Genetic Engineering

• Transgenic Organisms organisms that contain some
  genes from other organisms

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Transgenic Organisms are the basis for
Biotechnology!!!

• Transgenic bacteria now produce a host of
  important substances useful for health
  industry.
• Human insulin, growth hormone, and clotting
  factor are now produced by transgenic bacteria.
• Transgenic animals have been used to study genes
  and improve the food supply.
• These animals often grow faster and produce LESS
  fatty meat.
• Transgenic plants are an important part of our
  food supply.
• Many transgenic plants produce a natural
  insecticide, so the crops do not have to be
  sprayed with pesticides.

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Cloning a member of a population of genetically
identical cells produced from a single cell.
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CloningMeet Dolly the Sheep!!!