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DO NOW - NO TALKING PLEASE!!!

DO NOW - NO TALKING PLEASE!!!. What organelle is known as the control center of the cell? Mitochondria b) nucleus c) ribosome What are located on chromosomes? Genes b) alleles c) spindles d) RNA What are chromosomes composed of? RNA b) DNA c) tRNA d) mRNA. DNA: The Genetic Material.

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DO NOW - NO TALKING PLEASE!!!

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  1. DO NOW - NO TALKING PLEASE!!! • What organelle is known as the control center of the cell? • Mitochondria b) nucleus c) ribosome • What are located on chromosomes? • Genes b) alleles c) spindles d) RNA • What are chromosomes composed of? • RNA b) DNA c) tRNA d) mRNA

  2. DNA: The Genetic Material Chapter 12 Table of Contents Section 1 Identifying the Genetic Material Section 2 The Structure of DNA Section 3 The Replication of DNA

  3. Section 1 Identifying the Genetic Material Chapter 12 Objectives • Relate Griffith’s conclusions to the observations he made during the transformation experiments. • Summarize the steps involved in Avery’s transformation experiments, and state the results. • Evaluate the results of the Hershey and Chase experiment.

  4. Section 1 Identifying the Genetic Material Chapter 12 Transformation Griffith’s Experiments • Frederick Griffith (1928), bacteriologist • vaccine against pneumonia • Does anyone know what vaccine is? • substance prepared from killed or weakened disease-causing agents • Protects body from future infections

  5. Section 1 Identifying the Genetic Material Chapter 12 Griffith’s Discovery of Transformation

  6. Section 1 Identifying the Genetic Material Chapter 12 Transformation, continued Griffith’s Experiments • harmless bacteria  virulent when mixed with dead virulent • Now called transformation • cells take up foreign genetic material.

  7. Section 1 Identifying the Genetic Material Chapter 9 Transformation

  8. Section 1 Identifying the Genetic Material Chapter 9 Transformation, continued Avery’s Experiments • 1944 • Transformation not stopped by protein-destroying enzyme • Transformation is stopped by DNA-destroying enzyme • DNA is material responsible for transformation

  9. Section 1 Identifying the Genetic Material Chapter 9 Viral Genes and DNA DNA’s Role Revealed • Alfred Hershey, Martha Chase, 1952 • Used bacteriophage T2 to prove DNA carried genetic material. • Phages infects bacterial cells • Bacteria produces more viruses • Bacteria ruptures, releasing more phages

  10. Section 1 Identifying the Genetic Material Chapter 9 Bacteriophage

  11. Section 1 Identifying the Genetic Material Chapter 9 Viral Genes and DNA, continued Hershey Chase Experiment • Phage protein coat (outer) and DNA labeled with radioactive isotope. • Phage infects E. coli bacteria. • Bacteria spun to remove viral protein coat.

  12. Section 1 Identifying the Genetic Material Chapter 9 Viral Genes and DNA, continued Conclusion • DNA injected in, protein coat stays out. • DNA causes bacteria to make more virus. • DNA is hereditary material.

  13. Section 1 Identifying the Genetic Material Chapter 9 Hershey and Chase’s Experiment

  14. DO NOW – DO QUIETLY, NO NOTES • What is a vaccine? How is one typically made? • Define transformation. • What is a bacteriophage?

  15. Chapter 9 Section 2 The Structure of DNA Objectives • 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.

  16. Chapter 9 Section 2 The Structure of DNA DNA Overview Click to view clip

  17. Chapter 9 Section 2 The Structure of DNA A Winding Staircase • Shape discovered by Watson and Crick. • Doublehelix—looks like a twisted ladder. • Nucleotides are subunits of DNA • 3 parts • a phosphate group • a five-carbon sugar - deoxyribose • nitrogen-containing base.

  18. Chapter 9 Section 2 The Structure of DNA DNA Double Helix

  19. Chapter 9 Section 2 The Structure of DNA Double Helix Click to view clip

  20. Chapter 9 Section 2 The Structure of DNA Nucleotides Click to view clip

  21. Chapter 9 Section 2 The Structure of DNA A Winding Staircase, continued • Nitrogen bases: • Purine (Adenine or Guanine) • Pyrimidine (Thymine or Cytosine)

  22. Chapter 9 Section 2 The Structure of DNA Structure of a Nucleotide

  23. Chapter 9 Section 2 The Structure of DNA Discovering DNA’s Structure Chargaff’s Observations • Erwin Chargaff (1949) • Amount of adenine = amount of thymine (A=T). • Amount of guanine = amount of cytosine (G=C). • Total amounts of A/T, G/C varied between diff’t organisms.

  24. Chapter 9 Section 2 The Structure of DNA Discovering DNA’s Structure, continued Wilkins and Franklin’s Photographs • Wilkins and Franklin (1952) • High-quality X-ray photo of DNA. • Suggested a tightly-coiled helix shape.

  25. Chapter 9 Section 2 The Structure of DNA Discovering DNA’s Structure, continued Watson and Crick’s DNA Model • Watson and Crick (1953) • Uses Chargaff and Franklin’s work. • Builds model. • Double helix configuration. • Resembles “spiral staircase.”

  26. Chapter 9 Section 2 The Structure of DNA Discovering DNA’s Structure, continued Pairing Between Bases • Base-Pairing Rules • Adenine pairs with Thymine. • Guanine pairs with Cytosine. • Supported by Chargaff’s

  27. Chapter 9 Section 2 The Structure of DNA Discovering DNA’s Structure, continued

  28. Chapter 9 Section 2 The Structure of DNA Complementary Base Pairing

  29. Chapter 9 Section 3 The Replication of DNA Objectives • Summarize the process of DNA replication. • Describe how errors are corrected during DNA replication. • Compare the number of replication forks in prokaryotic and eukaryotic DNA.

  30. Chapter 9 Section 3 The Replication of DNA Roles of Enzymes in DNA Replication • Complementary structure of DNA used to make exact copies each time a cell divides. • Called DNA replication. • Occurs during synthesis (S) phase of the cell cycle, before cell divides.

  31. Chapter 9 Section 3 The Replication of DNA Roles of Enzymes in DNA Replication, continued • 3 steps: • DNA helicases (enzyme) unwinds, breaks rungs of double helix. • DNA polymerases (enzyme) moves along rungs, adds correct nucleotide to exposed base-pairs. • View demo • 2 identical DNA molecules formed.

  32. Chapter 9 Section 3 The Replication of DNA DNA Replication

  33. Chapter 9 Section 3 The Replication of DNA DNA Replication Click to view clip

  34. Chapter 9 Section 3 The Replication of DNA Roles of Enzymes in DNA Replication, continued Checking for Errors • Errors sometimes occur. • DNA polymerase (enzyme) “proofreads” new DNA. • Reduces errors to 1 per 1 billion nucleotides.

  35. Chapter 9 Section 3 The Replication of DNA The Rate of Replication • Replication does not start @ 1 end, end @ other – too long!!! • Human chromosomes replicated in about 100 sections. • Each section 100,000 nucleotides long. • Each section has own starting point (replication fork). • Entire human chromosome in 8 hours.

  36. Chapter 9 Section 3 The Replication of DNA Replication Forks

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