DNA Structure and Replication Chapter 14 (Chromatin in Chapter 10) - PowerPoint PPT Presentation

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DNA Structure and Replication Chapter 14 (Chromatin in Chapter 10)

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  1. DNA Structure and Replication Chapter 14 (Chromatin in Chapter 10) Topics you are not responsible for: Section 14.5: eukaryote replication Section (p 268-269) on ‘replisomes’ Be able to answer questions: Self-test #s 1 – 15 Challenge Question #1 3 MolnQuiry – Nucleic acids DNA Structure and Replication

  2. History of the discovery of the genetic material - 1? Bacteriophages infect Cells with DNA alone Alfred Hershey Martha Chase experiments -- 1928 -- radiolabled DNA and protein HC-Experiment DNA Structure and Replication

  3. What is the structure of • eukaryotic chromatin? • (from chapter 10) • Shape • Structure of chromatin • Nucleosomes • Functional areas • Centromeres • Telomeres • Replication Model supercoiling DNA Structure and Replication

  4. History of the discovery of the genetic material - 2? P.A. Levene showed DNA is a polymer of nucleotides Erwin Chargaff showed DNA composition differs among organisms DNA Structure and Replication

  5. What is the structure of a DNA strand? Nucleotides Phosphodiester linkages Sugar-Phosphate Bone 3’ to 5’ orientation Models DNA Structure and Replication

  6. History of the discovery of the genetic material - 3? J. Watson, F. Crick, R. Franklin and M. Wilkins Determined the 3-D structure What did Franklin and Wilkins contribute? Crystalography What did Watson and Crick Contribute? -- Double helix -- Antiparallel orientation -- Base pairing DNA Structure and Replication

  7. What is the structure of the DNA double helix? Complimentary base pairing -- base pairs are hydrogen bonded Antiparallel orientation Major and minor grooves Models Question DNA Structure and Replication

  8. How does DNA replicate -1? Semiconservative replication The M. Meselson and F Stahl experiment MS-Experiment DNA Structure and Replication

  9. How does DNA replicate -2? The need for RNA priming --”RNA Primase” Adding nucleotides -- “DNA Polymerase” 5’ to 3’ orientation Nucleotide Polymerization Question DNA Structure and Replication

  10. How does DNA replicate -3? Origins of Replication Replication ‘forks’ Replisomes DNA gyrase DNA Structure and Replication

  11. How does DNA replicate - 4? New strand 5 ‘  3’ orientation Leading & lagging strands DNA Helicase SS Binding protein RNA Primase DNA Polymerase III DNA Polymerase I Ligase Time DNA Replication I DNA Replication II DNA Structure and Replication

  12. How is genetic information encoded in DNA? Base sequence Organization into ‘genes’ How is genetic information used? “Transcription” of code from DNA to RNA “Translation” of code from RNA into A.A. sequence Question DNA Structure and Replication

  13. Sickle-cell anemia mutation What are mutations? -- see section chapter 20 section 20.2 Changes to the base sequence Some examples “Point Mutations” Base substitution Base deletion Base chemical change “Sequence mutations” Sequence inversions Triplet expansion “Chromosomal aberrations” Deletions Duplications Breakages Triplet expansion DNA Structure and Replication

  14. How is DNA damage repaired? DNA polymerase “proofreading” Mutation detection Excision repair (via endonuclease) Other repair enzymes photolyase thymine dimers Proofreading Excision Repair DNA Structure and Replication

  15. Acknowledgements and Sources DNA replication animations John L.Giannini;Biology Department, St.Olaf College http://www.stolaf.edu/people/giannini/biological%20anamations.html Hershey Chase experiment animation http://nortonbooks.com/college/biology/animations/ch12a02.htm DNA replication: http://highered.mcgraw-hill.com/olc/dl/120076/micro04.swf Trinucleotide repeat animation Howard Hughes Medical Institute http://www.hhmi.org/biointeractive/cancer/animations.html DNA Structure and Replication