Term
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Definition
1)G1 DNA-damage checkpoint=DNA has to be in good shape before cell can enter the cell cycle.
2)Restriction Checkpoint-Make sure everything is suitable before DNA replication (last part of G1)
3)S-phase DNA checkpoint-Middle of S phase, is it going or completed?
4)Unreplicated DNA damage checkpoint(end of S)
5)G2 DNA-damage checkpoint (repetitive)
6)Spindle-assembly checkpoint
7)Chromosome seperation checkpoint separate |
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Term
| Cell Cycle Checkpoints Overview |
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Definition
1)Arrest the cell cycle when genomic integrity is threatened.
2)Regulate cell cycle progression based on environmental signals (growth factors, extra-cellular matrix attachment, cell-cell contacts).
3)Checkpoints include an intra-S phase checkpoint, a spindle-assembly checkpoint, a spindle-position checkpoint and a DNA damage checkpoint.
4)Because of these critical functions, mutations in key checkpoint genes contribute to a variety of human diseases. |
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Term
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Definition
1)MPF (mitosis-promoting factor)
Regulates mitosis by activating:
a)Chromosome condensation
b)Nuclear membrane breakdown
c)Mitotic apparatus assembly
d)Chromosome alignment
2)Activates ANAPHASE-promoting complex (APC)***
3)Cyclins are then degraded by APC (Cyclins have to be degraded before cells can divide; phosphorylation dependent regulation of ubiquitation. Cdh1, cyclin that binds to APC is deactivation through phosphorylation and vice versa. can be induced by EXTERNAL or INTERNAL signaling) |
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Term
| Different phases in cell cycle |
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Definition
1) Mitotic-prophase, metaphase, anaphase.
2) Action steps of the cell cycle - S or the synthesis phase (where DNA incorporation occurs)
3) G1-restriction point or "start" phase are the the events leading to a decision--is the cell big enough? is the environment favorable? |
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Term
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Definition
| Critical step prior to mitosis where cell asks 1)Has all the DNA been replicated? Are there any errors? Is there DNA damage? |
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Term
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Definition
Exit from mitosis
Can the cell undergo cytokinesis? |
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Term
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Definition
Failure to interpret a checkpoint correct will result in progression before completion.
Mitotic catastrophe.
Chromosome breaks, misalignments, mis-segration. |
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Term
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Definition
1)You have
a)Growth Activators
b)Growth Inhibitors
2)Key players
a)Integrins
b)Nutrient status
3)Cell can go into
a)G0-quiescent (become terminally differentiated)
b)enter into active cell cycle |
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Term
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Definition
| Cyclin that together with Cyclin-Dependent Kinases control progression through the Cell Cycle |
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Term
| Pairings of cyclins with cyclin-dependent kinases |
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Definition
Multiple forms in mammalian cells
Cyclins D, E, A, B
CDK(CDC2)
Also, multiple cyclins can bind to the same cyclin kinase. |
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Term
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Definition
--CDKs:
1)do not exhibit kinase activity unless associated with a cyclin
2)9 Mammalian CDKs (not all cell are cycle genes)
--Cyclins:
1)concentration increase & decrease in phase with cell cycle
2)necessary for CDK activity and aid in substrate specificity
3)20 mammalian Cyclins
4)Classes of Cyclins:
a)G1 Cyclins – Help push a cell past the restriction point
b)G1/S Cyclins – act at the end of G1/ commit a cell to DNA replication
c)S-Cyclins – act in S to initiate DNA replication
d)M-Cyclins – promote the events of mitosis |
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Term
| General principles by which progression through the cell cycle is regulated |
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Definition
1)Activation of CDKs is driven by the sequential expression and association with cyclin subunits
2)The destruction of cyclins ensures a unidirectional cell cycle (presence of destruction box allows cyclin to be tagged by ubiquitin)
3)The inhibition of assembled CDK-cyclin complexes, either by phosphorylation or by the binding of inhibitory proteins (negative regulators) delays CDK activation and slows cell cycle progression in adverse conditions. |
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Term
| Mitosis is controlled by _____ |
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Definition
Matriculation Promotion Factor (MPF)
Low levels of cyclin & MPF activity during interphase (G1, S, G2) and high levels of cyclin & MPF activity during mitosis.
MPF artificially implanted in non-dividing cells undergo mitosis! |
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Term
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Definition
Machinery that connects sister chromatids.
Needs to be altered to allow seperation.
A Smc1Beta and Smc3 stalk on each of two subunits connected by Scc1. |
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Term
| Mechanism of action of APC |
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Definition
| Activates separase (though ubiquitination of securin), leading to cleavage of Kleisin (Scc1) |
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Term
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Definition
Likelihood of child born with Down Syndrome (Trisomy at chromosome 21) increases with maternal age.
This is because as mother gets older, 1 component of the cohesin component is lost or weakened (Smc1Beta) resulting in mis-separation during anaphase. |
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Term
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Definition
1)An cell cycle inhibitor
2)D2 (regulates start)
3)Retinoblastoma protein, Rb, is a critical substrate of cyclin D-CDK4/6 (complexed by D1 and D2) and Cyclin E-CDK2
4)Rb gets phosphorylated (goes from hypo-D-CDK4/6 to hyper (E-CDK2) through R point)
5)Rb is usually complexed with E2F (transcriptional activator) and phosphorylation of Rb leads to release of E2F.
6)Mutation in RB gene results in constitutive entry into the cell cycle. |
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