3.3.3 + 3.4.1

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3.3.3 + 3.4.1
2013-03-15 22:08:40

mitosis and DNA synthesis
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  1. (experiment on regulatory molecules) Conclusion
    M-phase contains a regulatory molecule that induces M-Phase in interphase cells
  2. What regulates MPF concentration?
    cyclin concentration
  3. (2)
    -MPF Cdk stays at the same concentration throughout the process

    -MPF Cyclin fluctuates in amount
  4. What does MPF stand for?
    Mitosis-Promoting Factor
  5. What does the MPF do?
    • this is present in the cytoplasm of the cells that are undergoing mitosis
    • *this is what set off the cells that were in the interphase in the previous experiment
  6. What does Cdk stand for?
    • cyclin-dependent kinases
    • *Has to do something with phosphorus
  7. What activates an MPF?
    • When cyclin and Cdk get together, a phsophate group is released from Cdk.
    • * dephosphorylation
  8. Cdk AND activating it
    It will only function when its own phosphate is removed
  9. (activated MPF has an array of effects) Phosphorylate chromosomal proteins
    initiate M phase
  10. (activated MPF has an array of effects) Phosphorylate nuclear lamins
    initiate nuclear envelope breakdown
  11. (activated MPF has an array of effects) Phosphorylate microtubule associated proteins.
    activate mitotic spindle
  12. (activated MPF has an array of effects) Phosphorylate an enzyme that degrades cyclin
    • cyclin concentrations decline
    • *this is why after mitosis cyclin levels fall to zero
  13. What is p53?
    a protein that is involved in checking for damaged DNA
  14. What happens if p53 finds a damaged DNA?
    • p53 activates genes that stop the cell cycle and lead to a cells programmed controlled destruction (suicide)
    • *apoptosis
  15. What does p53 inhibit?
    tumor formation
  16. What is p53 called also?
    tumor suppresor
  17. How did p53 get its name?
    protein with molecular weight of 53000 daltons
  18. What phase do mature cells go through?
  19. (checkpoints) G1 checkpoint requirements if..(4)
    -nutrients are sufficicent

    -growth factor are present

    -cell size is adequate

    -DNA is undamaged
  20. (checkpoints) If it passes G1 phase...
    the cell is allowed to proceed to S phase
  21. (checkpoints) G2 checkpoint requirements if...
    -chromosome replication is succesfully completed

    -no DNA damage

    -activated MPF present
  22. (checkpoints) If is passes G2 checkpoint..
    the cell goes through mitosis
  23. (checkpoints) Metaphase checkpoint requirements if..
    -all chromosomes are attached to mitotic spindle
  24. (checkpoints) What happens if they dont pass metaphase checkpoint?
    they do not proceed to cytokinesis
  25. (checkpoints) where do cells go after mitosis?
    G0 if they are mature cells
  26. How many origin places do bacterial chromosomes have ?
    just one

    top right
  27. How many points of origin do eukayotic chromosomes have?
    multiple points

  28. What is the replication fork?
    the area in eukarytoic cells where DNA is unzipping
  29. WHat is replication bubble?
    where the opening DNA synthesis is hapening
  30. Which side does replication occur in eukary?
    • proceeds in both directions from each starting point
    • *5>3 directions
  31. (synthesis of leading strand) first step
    - DNA is opened,unwound, and primed

  32. (synthesis of leading strand) first step
    (4) in depth

    -primase synthesizes RNA primer

    -topoisomerase relieves twisting force

    -helicase opens helix

    -SSBP stabilize single strands
  33. (synthesis of leading strand) 2nd step

    -synthesis of leading strand begins
  34. (synthesis of leading strand) 2nd step in depth

    -DNA polymerase III works in 5to3 direction synthesizing leading strand
  35. (synthesis of lagging strand) first step
    primase synthesizes RNA primer
  36. (synthesis of lagging strand) 2nd step
    DNA polymerase III works in 5to3, synthesizing first Okazaki fragment of laggin strand
  37. (synthesis of lagging strand) 3rd step
    primase and DNA polymerase III synthesize another Okazaki fragment
  38. (synthesis of lagging strand) 4th step
    DNA polymerase I removes ribonucloetides of primer, replaces them with deoxyribonucleotides in 5to3 direction
  39. (synthesis of lagging strand) 5th step
    DNA ligase closes gap in sugar phospahte backbone