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22 Cards in this Set
- Front
- Back
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Entry to mitosis requires:
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Activated MPF
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Proteins required for chromosome condensation at prophase
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condensin & topoisomerase II
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How are condensins and topoisomerase activated?
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Phosphorylation by MPF at onset of prophase
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What does APC-Cdh1 target for degradation?
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MPF (mitotic cyclins)
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What does cohesin do?
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Associates replicated DNA from s-phase to anaphase
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How does separation of sister chromatids occur?
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Degradation of securin, APC-Cdc20 activates separase which leads to proteolysis of securin
Securin = anaphase inhibitor |
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How does the nuclear lamina break down?
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Early prophase phosphorylation of serines, cause depolymerization of the lamina, which leads to nuclear envelope break down.
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What is the role of Cdc 14 in late anaphase?
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Reverse the effects of MPF: dephosphorylate nuclear membrane proteins,
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What stimulates mitotic spindle assembly?
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phosphorylation of MAPS (microtubule associated proteins) and myosin
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What promotes trafficking of vesicles to the ER?
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phosphorylation of ER and golgi proteins
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What causes nuclear pore disassembly?
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Phosphorylation of nuclear pore proteins
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What causes dissociation of chromatin from nuclear envelope?
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Phosphorylation of of inner nuclear membrane proteins
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What do cell cycle check points do? (2 things)
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1) Delay progression of cycle until DNA damage is repaired
2) Induce apoptosis if damage cannot be repaired |
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ATR pathway
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UV radiation (deals with multiple types of DNA breaks)
Kinase cascade leads to phosphorylation of Cdc25, inhibits MPF. G2 arrest |
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ATM Pathway
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Ionizing radiation (double strand DNA breaks)
Causes kinase cascade that stabilizes TF p53 by phosphorylation. |
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What does p53 stimulate? (2)
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1) cdk inhibitor p21cip (induces cell cycle arrest until DNA repair occurs or synthesis complete)
2) Can stimulate apoptosis if DNA damage is not repaired |
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What does the spindle assembly check point ensure?
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Prevents anaphase entry when even a single kinetochore from sister chromatids has not associated with the mitotic spindle.
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What is the spindle assembly check point protein?
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Mad2, inhibits APC-Cdc20
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How does Mad2 release from Cdc20
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p31 binds to Mad2 changing it to open conformation releasing Cdc20
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What does Cdc14 do?
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Dephosphorylates APC-Cdh1, allows it degrade mitotic cyclins, and thus exit from mitosis. It is release during proper chromosome segregation
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What does Cdc14 do to Sic1?
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It targets it for dephosphorylation, keeping S-phase cyclin cdks inactive in G1
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4 main checkpoints
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1) DNA damage
2) Unreplicated DNA 3) Spindle Assembly 4) Chromosome segregation |
