Genetic

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Genetic Engineering
MILLER-LEVINE BIOLOGY BOOK PAGES 247-259
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BREEDING TECHNIQUES
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Selective Breeding
Description ? The oldest and most obvious way of
improving species ? Select a few individuals to
serve as parents for the next generation ? Cross
individuals with a desired trait
Example(s) Luther Burbank produced 250 new
varieties of fruit in addition to the daisy and
Burbank Potato
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Inbreeding

• Description
• Technique used to maintain a stock of
  similar organisms
• Individuals with similar characteristics are
  crossed so the traits will appear again in next
  generation
• PROBLEM Increased risk of recessive genetic
  defects.

Example(s) Purebred dogs
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Hybridization

• Description
• A cross between dissimilar individuals of
  different, but related species
• Offspring are often hardier than either
  parent

Example(s) Commercially grown corn
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Mutagens

• Description
• ??????A breeder might not want to wait for a
  beneficial mutation to appear naturally. They
  catalyze this!
• ??????Mutagens include radiation and chemicals.
  They cause mutations
• With luck and time, breeders end up with
  good mutants

Example(s) Useful bacterial strains. Some
bacteria can digest oil are are useful in
cleaning up oil spills.
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GENETIC ENGINEERING
ARTIFICIALLY ALTERING GENETIC MAKE-UP, OFTEN
USING DNA FROM ONE ORGANISM IN ANOTHER
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STEP 1 ISOLATE THE DESIRED GENE

• Restriction Enzymes
• ??????Proteins that cut DNA sequences at specific
  regions
• More than 75 are known
• Each one recognizes a specific site of 4-6
  nucleotide pairs and cuts
• Make it possible to cut DNA into fragment
  that can be isolated, separated and analyzed

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STEP 2 COMBINE THE GENE(S) WITH DNA FROM
RECIPIENT ORGANISM

• DNA Recombination
• ??????Insert desired gene into organism--often
  bacterial plasmid (small circular pieces of
  bacterial DNA)
• DNA now consists of parts from different
  kinds of organisms
• This is recombinant DNA

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STEP 3 INSERT COMBINED DNA INTO NEW ORGANISM

• DNA Insertion
• ??????It is easiest to transfer DNA into
  bacterial cells
• Mix plasmids in with millions of bacteria in
  a salt solution
• Altered plasmids will carry foreign DNA into
  bacterial cells
• Bacteria are isolated and grown into large
  colonies to magnify the amount of the gene (DNA
  cloning)
• Using different techniques, recombinant DNA
  can be inserted into yeast cells, animals and
  plants

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GENETIC SCREENING
DETERMINING THE NUCLEOTIDES ON DNA, USING GEL
ELECROPHORESIS
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READ NEW SEQUENCES OF DNA

• DNA Sequencing
• Only one strand is used in DNA sequencing
• Many copies of the strand are needed and
  produced via DNA cloning
• Add radioactive phosphorus to DNA
• Divide DNA into 4 groups that undergo
  different chemical treatments that break DNA into
  pieces
• DNA pieces are separated by gel
  electrophoresis and banding patterns are analyzed
  to reveal sequence of bases

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TRANSGENIC ORGANISMS
ORGANISMS THAT CONTAIN FOREIGN GENES
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BACTERIA

• Description
• Organisms that contain foreign genes are
  transgenic
• When a gene coding for a human protein is
  inserted into bacteria, the recombinant cells may
  produce large amounts of the protein

Example(s) Human growth hormone, Insulin to
treat diabetes, Interferon to block growth of
viruses and treat cancer
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PLANTS

• Description
• DNA can be injected into plant cells
  directly or attached to plasmids of certain
  species of bacteria that infect plant cells

• Example(s)
• The goal is to produce plants that
  manufacture natural insecticides and fertilizer
• Firefly gene inserted into tobacco plant and
  it glowed!

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ANIMALS

• Description
• DNA can be introduced into reproductive
  cells by injection, among other techniques

• Example(s)
• Scientists introduced growth hormone gene
  from rainbow trout into carp. The new fish were
  bigger and faster growing.
• Another goal is to produce farm animals that
  are resistant to disease.

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CLONING
The production of genetically identical organisms
from single cells
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CLONED ANIMALS

• Description
• The nucleus of an egg cell is removed and
  replaced with a nucleus taken from an adult
  organism
• The egg is grown inside a foster mother
• The newborn is a genetic copy of the adult
  from which the nucleus was taken

• Example(s)
• In 1997 Dolly the sheep was cloned. Cows
  and mice have been cloned as well.

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GENE THERAPY Transgenic Humans
Genetic Engineering to treat disease
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GENETIC ENGINEERING IN HUMANS

• Description
• Transgenic humans can be produced by inserting
  foreign genes into human cells
• Remove cells from an individual and grow them
  in culture. Transform with a corrective gene and
  reinsert
• Viruses can be modified so they cannot cause
  disease

Now that you have some scientific background you
can make and support your arguments. Are you
FOR or AGAINST GENETIC ENGINEERING?

• Example(s)
• Cystic fibrosis, Tay-Sachs disease and
  sickle-cell anemia are examples of genetic
  disorders that could be treated in this manner

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Legislative Analyst - presents the necessary
scientific background required to understand the
genetic engineering application and the
proposition the law that is being proposed.
Paper and presentation should include Descriptio
n of proposition Explanation of SCIENCE
background relevant to proposition Proponent -
presents the argument in favor of the proposition
and the science supporting the proposition.
Paper and presentation should include Position
(YES on proposition) Explanation of SCIENCE in
support of proposition Relevant ethical issues
related to proposition Opponent - presents the
rebuttal to the argument in favor of the
proposition and the science against the
proposition. Paper and presentation should
include Position (NO on proposition) Explanati
on of SCIENCE against of proposition Relevant
ethical issues related to proposition