Chapter 16

  1. Frederick Griffith, in the 1920's, discovered the ____ ____.
    Transforming Principle
  2. What did Frederick Griffith study in order to discover the transforming principle?
    R strain & S strain Streptococcus Pneumoniae
  3. What are 4 characteristics of S strain Streptococcus bacterium?
    • Shiny, Smooth colonies
    • Capsulated
    • Virulent
    • Mice died within a day of being injected
  4. What are 3 characteristics of R strain Streptococcus bacterium?
    • Rough looking colonies
    • NOT capsulated
    • Nonvirulent
  5. What happened to Griffith's mice when they were injected w/dead S strain bacterium mixed w/live R strain & why?
    Mice died b/c S & R procreated & gene for capsulation transfered to R strain
  6. What were Griffith's 2 conclusions?
    • Living R strain transformed by presence of dead S strain
    • S & R strains procreate & gene for capsulation transfered to R
  7. Who discovered that the Griffith's transforming principle was actually DNA & when?
    Avery, McCleod & McCarty in 1944
  8. When Avery, McCleod & McCarty discovered that Griffith's transforming principle was actually DNA what were 2 reasons it wasn't readily accepted?
    • It was believed that DNA was too simple to be genetic material
    • Little known about bacterial genetics
  9. After doing their experiments, Avery, McCleod & McCarty, concluded that . . . .
    Transforming principle was indeed DNA
  10. What 2 scientists actually confirmed that DNA is indeed genetic material & when?
    Hershey & Chase in 1952
  11. What does a bacteriaphage do?
    • Lands on a cell
    • Injects bacterial DNA
    • DNA replicates
    • Cells Explode
    • Bacteria goes everywhere
  12. The T2 bacteriaphages utilized by Hershey & Chase were ____ that had their ___ packed in a protein coat.
    • E. Coli
    • DNA
  13. What 2 radioactive tracers did Hershey & Chase utilize & why?
    • Sulfur b/c its present in protein but not in DNA
    • Phosphorus b/c its present in DNA but not in protein
  14. After material is run thru a centrifuge the pellet is the ____ portion at the ____ & the supernatant is the ____ portion.
    • Solid
    • Bottom
    • Liquid
  15. In Hershey & Chases experiment, what was found to be in the supernatant?
    Sulfur & thus viral protein
  16. In Hershey & Chases experiment, what was found to be in the pellet?
    Compacted cells w/ phosphorus & thus viral DNA
  17. What was the conclusion of Hershey & Chases experiment?
    DNA enters bacterial cell & is responsible for reproduction of new viruses.
  18. Who determined the DNA NOT protein is genetic material?
    Hershey & Chase
  19. Who used X-ray crystallography to help to determine DNA structure & when?
    Rosalind Franklin & Maurice Wilkins in the 1950s
  20. Why did Franklin & Wilkins use X-ray crystallography to try to determine the shape of DNA?
    B/c the positions of atoms could be inferred fr the diffraction of X-ray being passed thru
  21. What did crystallographs taken by Franklin & Wilkins infer about DNA structure?
    That it was spiral or helical in shape
  22. What did Erwin Chargaff determine in the 1950's?
    Proportions of nucleotides in DNA
  23. Explains Chargaff's rule.
    Purines = Pyrimidines in DNA
  24. Chargaff's observations suggested the idea of ___ ___ ___ of DNA.
    Complimentary base pairing
  25. James Watson & Francis Crick did what in 1953?
    Utilized model building to est. general structure of DNA - Double helix
  26. What 3 results of previous experiments did Watson & Crick utilize?
    • X-ray crystalography
    • Chargaff's rule
    • Pauling's near miss
  27. What did Arthur Kornberg demonstrate in 1956?
    That DNA has info needed for its own replication
  28. Kornberg showed that DNA can replicate itself in a test tube if you have what 3 ingredients?
    • Template for DNA
    • DNA polymerase
    • Mix of 4 nucleotides
  29. Who determined that DNA replication IS a semi conservative process & when?
    Matthew Meselson & Franklin Stahl in 1957
  30. Meselson & Stahl utilized a procedure called ____ ____.
    Density Labeling
  31. What were Meselson & Stahl's 3 conclusions?
    • DNA replication is semi conservative
    • If replication was conservative then only heavy & light bands yielded
    • If replication dispersive then there would be no intermediate band in 2nd generation
  32. Nucleotides are made up of what 3 parts?
    • 5 C sugar (deoxyribose)
    • Phosphate Grp
    • Nitrogenous base
  33. What are the 4 nitrogenous bases that could make up a nucleotide?
    • Adenine
    • Thymine
    • Guanine
    • Cytosine
  34. What are the complimentary base pairs in nucleotides?
    • Thymine prs w/Adenine
    • Guanine prs w/Cytosine
  35. What type of bond holds complimentary base prs together in a nucleotide?
    Hydrogen Bonds
  36. The purines are ___ & ___ and the pyrimidines are the ___ & ___.
    • Guanine & Adenine
    • Cytosine & Thymine
  37. The type of DNA replication where each parent strand serves as a template for a new strand is ____ replication.
  38. What are 2 postulates of semi-conservative replication?
    • Each parent strand act as template for new strand
    • Each new double helix has 1 parent strand & 1 new strand
  39. The ____ strand runs fr 3' to 5' in the correct orientation for new nucleotides.
  40. The ____ strand runs fr 5' to 3' & is in reverse orientation.
  41. When the lagging strand in DNA replicates it does so in sm sections called ____ ____.
    Okazaki Fragments
  42. Okazaki fragments contain about how many nucleotides?
  43. What is the function of the DNA helicase?
    Unwinds double helix at the Ori into 2 forks
  44. Each new strand of DNA must be started by a ____ made of ___.
    • Primer
    • RNA
  45. The ____ forms an RNA primer.
  46. What eventually happens to the RNA primer?
    DNA polymerase I hydrolyzes RNA & replaces it w/DNA
  47. ___ ____ adds new nucleotides to the growing chain starting at the ___ end.
    • DNA Polymerase III
    • 3'
  48. There are multiple types of DNA polymerases. The 2 purposes we were told are . . . .
    • 1 is responsible for replication
    • Others remove primers or repair DNA
  49. What are 3 characteristics of the structure of DNA polymerases?
    • Much larger than substrates
    • Shaped like hand w/finger regions that rotate inward
    • Fingers have precise shapes that recognize shapes of bases
  50. ___ ___ catalyzes formation of phosphodiester linkage that joins Okazaki fragments together.
    DNA Ligase
  51. In prokaryotic cells 2 interlocking circular DNAs are formed separated by the enzyme ____.
  52. DNA replication in prokaryotic cells is short & circular & has ____ origin whereas in eukaryotic cells replication is ___ & ____ & has 100s of oris.
    • A single
    • Long & Linear
  53. What are the 2 major steps in DNA replication?
    • Double helix is unzipped by the helices
    • Nucleotides are added to 3' (OH) end of growing polynucleotide chain
  54. What are the 3 types of DNA repair mechanisms?
    • Proofreading
    • Mismatch repair
    • Excision repair
  55. Which form of DNA repair mechanism corrects errors during the replication process?
  56. Explain the proofreading repair mechanism.
    DNA polymerase proofreads its work during replication
  57. What is the error rate of the replication complex?
    1 in 10,000 base prs
  58. The repair mechanism that scans & repairs errors after replication is called ____ ____.
    Mismatch repair
  59. What errors is mismatch repair designed to get?
    Anything missed by DNA polymerase
  60. What repair mechanism operates over the life of the cell & repairs errors resulting fr chem or radiation damage?
    Excision repair
Card Set
Chapter 16
BI 253 ch 16