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Ch. 9 Notes DNA: The Genetic Material

Ch. 9 Notes DNA: The Genetic Material. By: Brianna Shields December 8, 2005. DO NOW. 1. Which scientist(s) “discovered” transformation? 2. Hershey and Chase verified the finding that what material is transferred during transformation?

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Ch. 9 Notes DNA: The Genetic Material

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  1. Ch. 9 NotesDNA: The Genetic Material By: Brianna Shields December 8, 2005

  2. DO NOW • 1. Which scientist(s) “discovered” transformation? • 2. Hershey and Chase verified the finding that what material is transferred during transformation? • 3. What type of lab organism did Hershey and Chase use in their experiments?

  3. Vaccine Virulent Transformation Bacteriophage Double Helix Nucleotide Deoxyribose Base-pairing Rules Complementary Base Pair DNA Replication DNA Helicase Replication Fork DNA Polymerase List the terms in your vocab notebook, leaving about 3-4 spaces between each term

  4. GOALS • Relate Griffith’s conclusions to the observations he made during the transformation experiments • Summarize the steps involved in Avery’s transformation experimentsand state the results • Evaluate the results of the Hershey and Chase experiment • Describe the three components of a nucleotide • Develop a model of the structure of a DNA molecule • Evaluate the contributions of Chargaff, Franklin and Wilkins in helping Watson and Crick determine the double helical structure of DNA • Relate the role of the base pairing rules to the structure of DNA • Summarize the process of DNA replication • Describe how errors are connected during DNA replication • Compare the number of replication forks in prokaryotic and eukaryotic DNA

  5. Griffith’s Experiment Trying to develop a vaccine (killed/weakened bacteria or virus introduced to body to protect from future infection) DNA: The Genetic Material

  6. Griffith’s Experiment Two strains of streptococcus pneumoniae S - virulent (disease causing), has capsule, grows in smooth colonies R- non disease causing, no capsule, grows in rough colonies DNA: The Genetic Material

  7. Griffith’s Experiment 1. Mice injected with S died 2. Mice injected with R were healthy DNA: The Genetic Material

  8. Griffith’s Experiment 3. Was bacterial capsule causing death in mice? DNA: The Genetic Material

  9. Griffith’s Experiment 4. Inject mice with dead S bacteria- mice remained healthy DNA: The Genetic Material

  10. Griffith’s Experiment 5. Injected mice with heat killed S bacteria- (can’t reproduce but still have capsule)- mice lived DNA: The Genetic Material

  11. Griffith’s Experiment 6. Injected mixed harmless live R with heat killed S into mice- mice died DNA: The Genetic Material

  12. Griffith’s Experiment 7. Mouse blood contained R bacteria that had acquired capsules (somehow changed and became virulent S bacteria) Discovered TRANSFORMATION DNA: The Genetic Material

  13. Griffith's Experiment

  14. Transformation Change in genotype caused when cells take in foreign genetic material DNA: The Genetic Material

  15. Avery’s Experiment What substance is responsible for transformation? Added protein destroying enzymes to heat killed S and healthy R mixture- transformation occurred Added DNA destroying enzymes to same mixture- transformation stopped DNA: The Genetic Material

  16. Hershey and Chase Experiment Wanted to confirm that DNA (not proteins) carried genetic material DNA: The Genetic Material

  17. Hershey and Chase Experiment Known facts A. Viruses made of DNA or RNA surrounded by protective protein coat DNA: The Genetic Material

  18. Hershey and Chase Experiment Known facts B. Bacteriophages (viruses) infecxt bacteria to produce more viruses (released when bacteria host ruptures) DNA: The Genetic Material

  19. Hershey and Chase Experiment Known facts C. Only DNA in phage contained phosphorus D. Only protein coat in phage contained sulfur DNA: The Genetic Material

  20. Hershey and Chase Experiment 1. Grew a sample of T2 bacteriophage in radioactive sulfur medium (would be used in T2’s protein coat) DNA: The Genetic Material

  21. Hershey and Chase Experiment 2. Grew a sample of T2 bacteriophage in radioactive phosphorus medium (would be used in T2’s DNA) DNA: The Genetic Material

  22. Hershey and Chase Experiment 3. Allowed S and P labeled phages to infect E. coli bacteria Can detect radioactive S and P to see if DNA, protein or both are transferred to E. coli DNA: The Genetic Material

  23. Hershey and Chase Experiment 4. S and P phages removed from bacteria using blender 5. Centifuge spins heavy bacteria to bottom and light phages to liquidy top of mixture DNA: The Genetic Material

  24. Hershey and Chase Experiment 6. Findings: A. S label found only in phages (protein never injected into E. coli) B. P label found mostly in bacteria (DNA transferred to E. coli) C. New generation of phages from bursted bacteria also contained radioactive DNA DNA: The Genetic Material

  25. Hershey and Chase Experiment 7. Conclusion: DNA is transferred from virus to bacteria Protein remains outside cell DNA must be hereditary material (atleast in viruses) DNA: The Genetic Material

  26. Assessment One • Summarize Griffith’s transformation experiments • Describe how Avery’s experiment supplied evidence that DNA, not protein is the genetic material • Describe the contributions of Hershey and Chase to the understanding that DNA is the genetic material • Why did heat kill Griffith’s S bacteria? • What might Hershey and Chase have concluded if they had found P and S in the bacteria cells?

  27. Watson and Crick Established the structure of DNA Made a tin and wire model of DNA DNA: The Genetic Material

  28. Structure of DNA 1. Double helix- 2 strands of linked nucleotides twisted around like a winding staircase DNA: The Genetic Material

  29. Structure of DNA 2. Nucleotides- subunits that make up DNA, composed of: Phosphate group Five carbon sugar molecule (deoxyribose) Nitrogen containing base (four kinds) Adenine Guanine Thymine Cytosine Bases pair up to create” ladder rungs” DNA: The Genetic Material

  30. Structure of DNA 3. Base classification Purines- double ring of C and N atoms Adenine and Guanine Pyrimidines- single ring of C and N atoms Thymine and Cytosine DNA: The Genetic Material

  31. Structure of DNA 4. Helix held together by weak hydrogen bonds between paired bases DNA: The Genetic Material

  32. Chargaff Discovered base pairing rule Amounts of adenine and thymine in DNA are always the same Amounts of cytosine and guanine in DNA are always the same Amounts of A and T, and G and C differ DNA: The Genetic Material

  33. Wilkins and Franklins Photographs Bounced X rays off DNA to create pattern scattered onto film Photos indicate DNA is a tightly coiled helix with 2 chains of nucleotides DNA: The Genetic Material

  34. Pairing between bases Because of size and structure of bases, only certain ones pair up to hold DNA together Adenine - Thymine Guanine - Cytosine DNA: The Genetic Material

  35. Pairing between bases Results in complementary base pairs Sequence on one strand of DNA can determine sequence of other strand DNA: The Genetic Material

  36. Assessment Two • Describe the three parts of a DNA molecule • Relate the base pairing rules to the structure of the DNA • Describe the two pieces of information from other scientists that enabled Watsons and Crick to discover the double helical structure of DNA • Explain why the two strands of the double helix are described as complementary • What would be the complementary strand to DNA with the following base sequence: AGCTTAGTCA

  37. Replication of DNA Making a copy of DNA Complementary strands of DNA serve as template for replicating DNA Occurs during S phase of cell cycle (before division) DNA: The Genetic Material

  38. Replication of DNA Steps: A. DNA helicase unwinds and opens DNA by breaking H bonds between bases DNA: The Genetic Material

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