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17 Cards in this Set
- Front
- Back
interphase
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all periods of the cell cycle except for mitosis or meiosis
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g1 phase
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Gap 1 = period following mitosis/meiosis w/ no dna replication
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g0 phase
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secescent phase; arrested g1 phase ; cells that cease to divide go into this phase
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S phase
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synthetic phase; period of dna replication
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g2 phase
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period between dna replication completion and the onset of mitosis
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cyclins
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major cell cycle regulatory proteins, mRNA /protein levels oscillate throughout cell cycle ; cyclin degradation allows for cell cycle phases to progress
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g1 cyclins ; C,D,E
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C,D,E, expressed during G1 phase, controls progression of g1-s phase
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g2 cyclins; A,B
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A,B expressed during g2/m stages ; controls g2--> m progression
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Cyclin dependent kinases
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kinases that are activated by cyclin binding ; cdk levels dont change during cell cycle but ENZYMATIC activities DO CHANGE ; kinases PHOSPHORYLATE threonine/tyrosine residues
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G1 CDK'S
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Cdk2,4 ; activated by G1 cyclins
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cdc2 (g2 CDK)
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bound and activated by g2 cyclins
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MPF - mitotic promoting factor
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G2 CYCLIN/ cdc2 complexes induce mitosis via phosphorylation of NUCLEAR LAMINS and H1 HISTONES
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Checkpoints
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signals that decide to progress to different phases of the cell cycle
- function --> block cell cycle progression until dna damage c |
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tumor suppressors
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p53/rb
- checkpoints are mediated by tumor suppressors --> inhibit cell cycle progression |
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Retinoblastoma (RB)
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tmr suppressor
- blocks g1-->s progression until G1 CYCLIN/Cdk complexes reach critical level - mid G1--> hyprphsphryltn causes release of E2F --> causes progrssion to s-phase - e2f activtes e2f transcription as well as g1/cyclin cdk activation --> causes + feedback and faster initiation of s-phase |
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p53
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-rspnds to dna damage
-blocks cc progression or induces apoptosis - p53 actviates p21 - p21 inhibits ALL G1/G2 cyclin/cdk complexes --> thus blocking cc progression @ g1-S and g2-m transitions |
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if dna damage is too bad, what happens?
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p53 initiations apoptosis via BAX
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