DNA Replication S1M1

  1. What does it mean to be anti parrallel in nature, speaking of a DNA strand
    The two strands of DNA run 5' to 3' in opposite directions
  2. During what phase is DNA copied
    The S phase (DNA Synthesis)
  3. DNA replication is said to be semi conservative, why
    In the end, one rung is new, and one rung is old
  4. How long is the S phase
    A few hours
  5. What is a replication fork
    An area where the DNA into two strands and DNA synthesis occurs
  6. What is an ORC, and what is its job
    ORC stands for Origin Recognition Complex, it binds to origins of replication to begin replication
  7. What other enzymes does the ORC attract for replication
    • Cdc6 (loads MCM with help from Cdt1)
    • MCM helicase
  8. Geminin does what
    Inhibits Cdt1 and pre-RC formation
  9. CDK and DDK become active when and have what role
    In late G1, they activate MCM and load the replisome
  10. What must happen for replication to start even after all the enzyme are in place
    The ORC, Cdc6p, and MCM must be phosphorylated
  11. How does CDK and DDK inhibit the ORC from replicating more than once a cycle
    By Phophorilating S1d2, S1d3 proteins, and MCM
  12. What does the DNA Helicase do
    It seperates the DNA helix
  13. What is used to prevent overwinding of the DNA during replication
    Topoisomerase (Gerase), this splices the DNA allowing it to unwind then seals it back up
  14. What happens to the DNA when part of it is unwound
    It creates supercoils further down the line
  15. SSB's Single Stranded Binding Proteins have what role
    They prevent the double helix from reforming temporarily
  16. What is Camptothecin
    It is a Topoisomerase 1 inhibitor, and is used to treat cancer
  17. What is Etoposide
    It is a Topoisomerase 2 inhibitor and is used to treat cancer
  18. What is the difference between Topo 1 and 2
    • Topo 1 cuts just one strand of DNA to release the tension
    • Topo 2 cuts both strands
  19. Inhibitors of DNA replication are most likely to find medical use as
    Anti-cancer drugs
  20. DNA polymerase β functions in
    DNA repair
  21. DNA polymerase α is composed of and does what
    • Made of an RNA polymerase and a DNA polymerase
    • It builds an RNA primer starting at the 5' end
  22. What are the main DNA polymerases and they require what
    Polymerases δ and ε and need a 3’OH to polymerize more nucleotides
  23. What is the polymerase that builds the RNA primer at the 5' end of a new DNA strand in Eukaryotes
    DNA polymerase Alpha
  24. Pol ε is assigned to the
    Leading strand
  25. Polymerase delta is assigned to the
    Lagging strand
  26. What does PCNA do
    It keeps the DNA polymerase on the DNA
  27. What is an RNA primer
    • It is the primer to the paint, it is the first portion of the new DNA strand which is necessary for the rest of the strand to stick
    • Added by polyemerase alpha
  28. What is the leading strand
    • Strand that is making DNA toward the replication fork
    • It uses Polymerase epsilon
  29. How is the lagging strand different
    It makes the DNA away from the replication fork and can only do it in short fragments
  30. DNA is built in what direction
    5'-3' ALWAYS!!
  31. What kind of bonds are formed to make a new strand of DNA
    Covalent, Hydrogen bonds between the bases
  32. What is an ozarki fragment
    In the lagging strand, it is the short fragments that are being replicated
  33. How are the gaps made by the ozarki fragments filled
    A DNA ligase finishes the bond after the primer is removed by a phosphodiester bond
  34. When the gaps on the Ozarki fragments are filled, the ribonucleotides are replaced with
  35. What enzyme is necessary to seal the phosphodiester backbone and fuse Ozarki fragments together?
  36. What removes the RNA primer from the DNA
    RNase H
  37. The lagging strand of telomeres cannot be replicated by the usual mechanism, the solution is
    A special telomere sequence: tandom repeats of TTAGGG
  38. Telomerase is
    • An enzyme that adds nucleotides to telomeres so that the last portion of the DNA that the lagging strang can't normally transcribe is transcribed leaaving only the repeat of TTAGGG on the end.
    • Found especially in cancer cells
  39. What kind of enzyme is telomerase
    A RNA-dependant DNA polymerase
  40. Cells are more susceptible to mutations when
    During the S stage
Card Set
DNA Replication S1M1