bio exam 4 part 4

  1. what percentage of cells are in G0 phase
    99.999% of cells
  2. do all species control the cell cycle the same way
  3. how does cell cycle start off
    origin of replication, triggers replication of replicon near it
  4. when is each origin licenesed
    during interphase
  5. when does pre-replication complex break down
    when replication starts
  6. what happens in G1 phase
    • where cells are born
    • physical growth stay in cell cycle or exit to GO
    • contains a restriction point
  7. for what reasons would a cell not pass the first restriction point
    if starved, external signals, or inhibitory signals
  8. G0 phase
    most cells in the body are in G0 phase
  9. what happens in S phase
    • each licensed origin fire simultaneously
    • triggered by kinases, takes minutes
    • pre-RC dismantles and is not rebuilt again until G1
  10. how long is one replicon
    ~3,000 bases
  11. how are sister chromatids linked together
    cohesin proteins, only releases during mitosis
  12. what happens in G2 phase
    • very brief, quickest, part of the cell cycle
    • cells start to accumulate chemical signals to activate mitosis (cyclins)
    • contains second restriction checkpoint
  13. cytoplasmisis
    physical separation of cytoplasm cut in half
  14. parts of mitosis
    • prophase
    • prometaphase
    • metaphase
    • anaphase
    • telophase
  15. what happens in prophase
    • chromatin folds up into loops and condenser-cohesins hold them together
    • cytoskeleton rearrangements
    • dynamic instability
    • centrosomes duplicate and divide
    • centrioles and pericentriolar material nucleates MTs
    • forms mitotic spindle poles
  16. what happens in prometaphase
    • nucelar envelope dissolves due to increased cyclin/cdks
    • kinetochores of chromosomes bind (+) end of MTs
    • unattached kinetechores give signals that inhibit mitosis
  17. what happens in metaphase
    brief moment when chromosomes are perfectly lined up
  18. what happens in anaphase
    sister chromatids release each other-triggered by phosphorylation and proteases that cut cohesins
  19. anaphase A vs. B
    • A-MTs move toward the poles
    • B-poles move themselves toward the end of the cell
  20. what happens in telophase
    chromatin ends up on opposite side of the cell and nucleus reforms
  21. what controls cell cycle
    kinases(only active when bound to cyclins)
  22. what always exist at the same concentration
  23. main cdk responsible for G1 restriction point
  24. main cdk responsible for G2-metaphase transition and M phase
  25. how are cyclins regulated
    by transcription and translation
  26. What cyclin is at its peak at the beginning of Mphase
  27. What cyclin is at its peak at the beginning of anaphase
  28. What cyclin is at its peak at G1/S
  29. how are cdks regulated
    phosphorylation and cyclin activating kinases
  30. things that cdk1 PO in prophase
    • lamins-N.E
    • LIS-I, NDE- increase affinity for dyneins that rip-off chuckcs of N.E
    • GRASP65-results in reduced golgi stacking
    • COPI-allows golgi vessicles to form but it can't re-fuse
    • COPII-prevent ER-golgi trafficking
    • histone H1-creates higher affinity for self assembly
    • kinesin5-causes it to walk toward + end and push MTs and centrioles apart
    • MAPS-dissociate from MTs, result in distabilization(dynamic instability)
  31. 3 classes of MTs
    • Astral Mts-points toward back of the cell
    • polar overlap-MTOC and toward each other
    • kinetochore
  32. function/structure of PO kinesin5
    • bipolar kinesin (2 molecules)
    • bind to two opposite direction MTs and push them against each other to opposing poles
  33. what modulates chromatin condensation
    cohesins and condensins
Card Set
bio exam 4 part 4