Language of Life

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• Chapter 14

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Language of Life

• Protein or DNA

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Griffith Experiment
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Nature of DNA

• Friedrich Miescher 1869 discovered nuclein
• Robert Feulgen 1914 discovered that DNA was
  attracted to the dye fuchsin
• 1920s P.A. Levine
• DNA could be broken down into 5-C sugar, four
  nitrogenous base, and a phosphate group
• Made two deductions
• Tetranucleotide
• Linking of groups

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Max Delbruck Salvadpr Luria1940

• Looked for another fit genetic subject
• Bacteriophage that eats E. coli
• Most work was done with the T2 T4 series

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32P 35S
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Chargaffs Results

• Erwin Chargaff of Colombia Universitys College
  of Physicians and Surgeons

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4 requirements of genetic material

• Continue from generation to generation
• Produce information for being copied
• Chemically stable
• Capable of mutation

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Watson-Crick ModelKnown Data

• Very large with A,T,G,C
• Levenes hypothesis tetranucleotide
• Linus Pauling (1950) protein can be found in
  helix
• Xray diffraction Maurice Wilkins and Rosalind
  Franklin lent to idea of giant helix
• Chargaffs rule

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Building the Model

• Complementary strands
• Directionality
• 5?3 and 3?5

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G
C
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DNA Replication

• Template
• Semiconservative replication

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Matthew Meselson Franklin W. Stahl confirm
semi-conservative replication

• Heavy isotope of 15N CsCl

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