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Discovering DNA as Genetic Material

Learn about historical discoveries regarding DNA as the genetic material in biology. Topics include Avery's and Hershey-Chase's experiments.

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Discovering DNA as Genetic Material

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  1. Review Chapter 8 Test Notes – Chapter 9 When you fall, pick something up." Oswald Avery To learn about the historical discoveries surrounding the genetic material, DNA. Title: Biology 3/8/07 Class Topics Objectives: Thursday, January 2, 20208:55 PM

  2. Class Assignments What By When • W.S. 9.1 3/8/07 • Chapter 9 Quiz 1 3/12/07 • Due this class period • Due next class period • Due in the future

  3. Grade Sheet 2A – p. 157 (5 pts.)

  4. Avery’s conclusion • Carbohydrase didn’t block transformation • Proteases didn’t block Transformation • Ribonuclease didn’t block transformation • Deoxyribonuclease blocked transformation • What’s the conclusion? • DNA is the genetic material of bacteria

  5. Avery’s experiment • Problem • Hypothesis • Procedure • Conclusion

  6. From: http://ribonode.ucsc.edu/HuGen/01_80H/01_80Hlec6.html

  7. Hershey-Chase Experiment • 1952 - Alfred Hershey and Martha Chase worked with viruses to support the conclusion that DNA is the genetic material • The specific viruses were bacteriophages (phages) • infects bacteria • Contain both DNA and Protein

  8. Radioactive Isotopes • Isotope - same element (number of protons) but different numbers of neutrons • Unstable or radioactive (releases energy) • Used to follow the different elements throughout the experiment • Phosphorus-32 - DNA not protein • Sulfur-35 - protein not DNA

  9. Graphic taken from the MIT Hypertext

  10. From: http://osulibrary.orst.edu/specialcollections/coll/pauling/dna/pictures/hersheychase-experiment.html

  11. Chapter 9 Quiz 1 Review • Describe 1 of the 3 experiments • Griffith, Avery, or Hershey/Chase • Problem • Hypothesis • Procedure • control & experimental groups, independent & dependent variables • Data • Conclusion

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