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10 Cards in this Set
- Front
- Back
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Describe the stages of the cell cycle
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M = mitosis (cell division)
G1 = normal cell function, normal metabolism, if you have a cell that is non dividing it is stuck in G1 phase S phase – DNA synthesis G2 phase – between DNA duplicaiton and cell division – may grow a little more |
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Define CDK and Cyclins
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Cyclins: Regulatory subunit that confer target specificity
CDK: Cyclin dependent kinase - is a catalytic subunit that is inactive without cyclin |
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What are the two steps for CDK activation?
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1) Cylin binds and removes the blocking protien slap, loosening the t-loop.
2) CDK activating kinsase (CAK) comes in and phosphorilates the cyclin to make it fully active. |
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What two cycles does cyclin undergo?
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Synthesis and degredation due to ubiquitin.
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Name the 4 cyclins and at what step in the cell cycle they are utilized.
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Cyclin D: found throughout the all phases
Cyclin E: Commits cell to DNA replication. Found in G1-S phase Cyclin A: Required to proceed through S phase. Starts in G1, peaks in G2 and drops at start of Mitosis. Cyclin B: Promotes mitosis. Starts in S-phase, peaks and falls at start of Mitosis. |
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Know the names of the complexes associated with the types of cyclin (D, E, A, B).
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Cyclin D = G1-Cdk
Cyclin E = G1/S-Cdk Cyclin A = S-Cdk Cyclin B = M-Cdk |
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What are the three checkpoints and when do they occur?
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M checkpoint - during Mitosis, checks to see if chromosomes are properly aligned and attached to spindle.
G2 checkpoint - before M phase, checks if all DNA is replicated and no mistakes. G1 checkpoint - before S phase, checks to make sure DNA is ok |
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Name the two main DNA damage checkpoints
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Late G1 and late G2.
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Define Rb and describe how it works and why it's important for transitioning into S-phase.
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Rb = Retinoblastoma. As long as Rb binds to E2F, E2F remains inactive. Once Rb is phosphorylated by cycline CDK complex, it releases E2F to take over transcription phase and move into S-phase.
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What occurs in termainlly differentiated cells?
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They remain in the G1 or G0 phase.
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