26 - Cell Proliferation Flashcards
Function of G1 cyclin-GDK complexes
Prepare the cell for S phase
Stuff on G1, and S phase
Paul Nurse 1996
- asked if the Sz pombe (a fungi/yeast) cell cycle can run with just one CDK, can it also run with just one cyclin
- found that the yeast had 4 cyclins, and one CDK
Experiment - can yeast cell division occur with minimal CDK control - one CDK and one cyclin?
- how?
Yes
- G1 targets in the cell cycle are high affinity targets, even for simple CDK-cyclin fusions/complexes
- so the complexes are able to phosphorylase G1 targets, and allows entry into the S phase of interphase
Implications of minimal CDK-cyclin complexes being able to phosphorylase G1 targets,and move cell into S phase
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Comparison between free-living motile unicells (bacteria, prokaryotes etc.) and immobile cells in a complex body
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Do mammalian cells have a quiescent phase
- what is a quiescent phase
Yes
- …
Quiescent phase in mammalian cells info
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G0 and cancer
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G0 phase function
Allows differentiation and proliferation in cells
- allows cell specialisation
G0 phase in interphase info
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At what point can cells in G1 phase not pass into G0 phase
The restriction point
- after this, cells must move into S phase
Mitogenic signals - activation of growth factor receptors process
- growth signals start at plasma membrane, by binding of specific ligands (EGF, EGFR) to specific receptors
- growth factor binding dimerises the receptors
- this auto-phosphorylates the receptors
- resulting in activation of the growth factor receptors
What can go wrong with growth factor receptors
Mutational activation of receptors could occur:
- many breast cancers have a mutation in the trans-membrane domain of the c-erbB1 growth factor receptor
- so receptor would be self-activating, dimerising and phosphorylating in absence of a growth factor
- so unregulated proliferation and cell division would occur
Viral subversion:
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