Biotechnology

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Biotechnology

• Biotechnology

• Techniques used to manipulate DNA

• Many applications

• Medical

• Bacterial production of human insulin

• Animal science

• Bacterial production of BST to increase milk
  production

• Horticultural

• Transgenic crops with herbicide resistance or
  nutrient enhancement

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Biotechnology

• Stages of genetic engineering

• DNA cleavage

• Source DNA (with gene of interest) broken into
  fragments by enzymes

• DNA fragments visualized by electrophoresis

• Bigger fragments move through gel more slowly
  when electric current applied

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Biotechnology

• Stages of genetic engineering

• Production of recombinant DNA

• DNA fragments inserted into viral or bacterial
  DNA (recombinant DNA)

• e.g. DNA from source inserted into circular
  chromosome of bacteria called plasmid

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Biotechnology

• Stages of genetic engineering

• Cloning

• Bacteria or virus with source DNA introduced into
  cells of interest (often bacteria)

• Cells reproduce asexually to produce clones

• Cells with different fragments maintained
  separately (produce clone library)

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Biotechnology

• Stages of genetic engineering

• Screening

• Clones with DNA fragment of interest (fragment
  with desired gene) identified

• Bacterial plasmid contains gene for antibiotic
  resistance

• Cells without plasmid fragments susceptible to
  antibiotic

STEP 1 remove cells without plasmid
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Biotechnology

• Stages of genetic engineering

• Screening

• Clones with DNA fragment of interest (fragment
  with desired gene) identified

• Bacterial plasmid contains gene for enzyme that
  metabolizes sugar (X-gal)

• If source DNA inserted in this gene, no sugar
  metabolism occurs

STEP 2 eliminate cells without source DNA
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Biotechnology

• Stages of genetic engineering

• Screening

• Clones with DNA fragment of interest identified

• Hybridization used to locate gene of interest

Step 3 locate gene of interest
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Biotechnology

• Horticultural applications of genetic engineering

• Produce transgenic plants

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Biotechnology

• Horticultural applications of genetic engineering

• Ethylene inhibition

• Carnations insensitive to ethylene last longer
  when cut

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Biotechnology

• Horticultural applications of genetic engineering

• Herbicide resistance

• Transgenic soybeans tolerant to active ingredient
  in Roundup, a commonly used herbicide

• In 1999, 50 of soybeans in US transgenic strains

• Used in many other plants (e.g. petunia)

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Biotechnology

• Horticultural applications of genetic engineering

• Nitrogen fixation

• Incorporate genes of nitrogen-fixing bacteria
  into crops to reduce the use of fertilizers

Root nodule containing nitrogen-fixing bacteria
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Biotechnology

• Horticultural applications of genetic engineering

• Insect resistance

• Incorporate Bt gene into crops

• Bt gene produces protein that is toxic when
  ingested by insect larvae

• Approved by EPA for potato, cotton, tobacco,
  corn, tomato and other crops

• Possible detrimental effects on harmless insects
  such as monarch butterflies

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Biotechnology

• Horticultural applications of genetic engineering

• Added nutrients