Topic 8 From Gene to Protein

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Topic 8 From Gene to Protein
Biology 1001 October 14, 2005
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I. Overview of Protein Synthesis

• How does the specific sequence of nucleotides
  along a DNA strand determine an organisms
  traits?
• DNA directs the synthesis of proteins, a process
  called gene expression
• Proteins are the link between the genotype the
  phenotype
• The flow of information from gene to protein has
  two stages
• The synthesis of mRNA under the direction of DNA
  transcription
• The synthesis of a polypeptide under the
  direction of mRNA translation

Figure 17.3
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II. Evidence for the control of metabolism by DNA

• In 1909, Archibald Garrod postulated that
  inherited disease - inborn errors of metabolism
  - reflect an inability to make particular
  enzymes
• Cells synthesize and degrade organic molecules
  using metabolic pathways, the steps of which are
  catalyzed by enzymes
• A mutation in the gene coding for a particular
  enzyme leads to a change in the product of a
  pathway
• Originally called the one gene-one enzyme
  hypothesis, now referred to as the one gene-one
  polypeptide hypothesis of gene expression

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Albinism is an inborn error of melanin
metabolism
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More Albinos