Biology 1111

1
Lecture 27

• Biology 1111
• Chapter 12 DNA Technology and the Human Genome

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Learning Objectives

• Define
• Genetic marker
• Explain
• RFLP
• Junk DNA
• Gene therapy
• List benefits and pitfalls of PCR

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Genetic Markers

• Any sequence of DNA varying from individual to
  individual
• Most similar in relatives
• Can be coding DNA (for polypeptides) or junk
  DNA (non-coding)

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Restriction Fragments

• Pieces of DNA cut by restriction enzymes
• Cutting may differ from person to person
  (polymorphism)
• Unique combination of fragments occurs

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Restriction Fragment Analysis

• RFLP restriction fragment length polymorphism
• Only 1 drop blood needed!
• Example Individual 1 is a carrier
• What about 2, 3?

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RFLP in Court
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Polymerase Chain Reaction (PCR)

• Makes copies of DNA in test tube chemically (no
  cells required)
• Makes copies of copies (chain reaction)
• Amplifies DNA
• Key ingredients
• DNA polymerase (a special one, from bacteria
  living in Yellowstone geysers!)
• Single nucleotides

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Benefits of PCR

• Faster than bacterial cloning (a few hours vs.
  days)
• Can be used on tiny DNA samples
• Amplification allows for analysis by other
  methods like RFLP
• Even less than 1 drop of blood!
• Tiny bits of tissue
• Mummies
• Rare fossil DNA
• Museum specimens of plants animals

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Problems with PCR

• Copying not perfect can introduce errors
• Errors may be copied over over
• Will also amplify contamination!
• Sloppy lab work will ruin
• Potential museum problem Bacteria in tissue
  samples
• Jurassic Park Problem Dino DNA from mosquito?

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Junk DNA

• Human DNA codes for
• Proteins (typical example)
• RNA (like tRNA and rRNA)
• Promoters, operators
• But, 97 codes for nothing at all!
• We call it junk DNA
• Maybe we just dont know function yet

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Human Genome Project

• DNA sequencing complete, but most interesting
  work is yet to come!
• Humans have only 2-3X more genes than fruit flies
  and nematode worms!
• Also, mapping of other organisms allows for
  comparison
• Sharks hardly ever get cancerhmm
• Knowledge of other organisms proteins gives
  hints to human protein functions

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7th Inning Stretch
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Genetically Engineered Organisms

• Bacteria can grow
• Insulin treats diabetes
• Human growth hormone treats growth defects
• Taxol treats ovarian cancer
• Yeast can produce
• Hepatitis B vaccine
• Mammalian cells produce
• Erythropoietin (EPO) treats anemia
• Tissue plasminogen activator (TPA) treats heart
  attacks

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Better Medicines from Cloned Genes

• Before bacterial cloning
• Insulin was isolated from pig and cattle tissues
• Not identical to human insulin
• Growth hormone only available from cadavers
• Supply was very limited

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Vaccines from DNA Technology

• Bacteria can be used to manufacture Hepatitis B
  virus proteins
• Injected into patients, this prompts immune
  system to make antibodies
• Immunity to Hepatitis B results

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Miraculous GM Rice

• Rice staple for half of worlds population
• Genetically modified (GM) golden rice carries
  daffodil genes for beta-carotene (vitamin A
  precursor)
• Can help people in developing countries where
  vitamin A deficiency is problem (blindness)

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Gene Therapy Science Future?

• Theoretically possible to give patients desired
  copies of genes
• Bone marrow cells prime candidates for receipt of
  gene transplant. Why?

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Gene Therapy is Short-term

• Problem most of gene therapy appears to be
  short-term
• Expression of transplanted genes seems to fall
  off over time
• Best application will be short term
• After heart attack, stimulate growth of new blood
  vessels around blocked ones

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Regulation of GM Experiments

• U.S. and others have stringent safety standards
• Prevent infection of lab workers by GM organisms
• Create GM organisms which can only live in the
  lab (they need us to provide a nutrient)
• Ban dangerous experiments (ie cancer genes into
  bacteria)