Chapter 16: The Molecular Basis of Inheritance

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Chapter 16 The Molecular Basis of Inheritance

• AP Biology
• Mrs. Ramon

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What is the genetic material?

• What was known
• 1940s ? Chromosomes are carriers of hereditary
  information
• Chromosomes consist of two substances
• DNA
• Proteins
• The Arguments
• Protein Camp
• DNA Camp

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The Evidence - Griffith
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More Evidence Avery, McCarty and MacLeod

• (1944) Purification of various components from
  heat-killed S cells were tested with live R cells
  to test for transformation

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The Clincher Hershey Chase

• Genetic material was transferred from a viral
  phage to E. coli during infection
• Differentially radioactively labeled proteins and
  DNA
• Labeled DNA was detected

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But what does it look like?

• Structure of DNA
• Chargaff (1947)
• Analyzed base composition of DNA from different
  organisms
• DNA composition is species specific
• Amounts of the four bases are not equal
• Ratios of bases vary
• Chargaffs rules
• A T
• C G

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DNA Structure The Model

• Rosalind Franklin
• X-ray image of DNA
• Watson and Crick
• Model of DNA
• Nobel Prize (1962)

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The Structure of DNA

• Double helix
• Antiparallel strands

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Watson-Crick Base Pairing
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