15. Cell Cycle Regulation Flashcards
what do cells in G1 respond to
what happens if levels are sufficient?
growth factors
cell will progress into M phase
why must cyclins be degraded
to prevent the cell cycle reoccurring
this maintains unidirectionality
what cyclin is important in M-phase
cyclin B- CDK1
what cyclin is important during G2 phase
cyclin A - CDK2
what molecule is essential at regulating cell cycle transitions
cyclins
what gene is targeted via signalling to allow cyclin D and E2f expression
Myc
describe the process of mitogen dependent signalling
- cells receive mitogens from adjacent cells (paracrine signalling)
- binding of mitogen receptor activates GRB2, and Sos and eventually Ras
- Ras binding recruits a MAPK cascade
- Transcriptional activation of Myc
what type of gene is Myc
regulatory gene
what is the function of Myc
cyclin D and E2f expression
what is E2f
transcriptional regulator of S-phase genes and cyclins E and A (regulatory cyclins of S phase)
what must CDKs have to be active
their cyclin binding partner
e.g. cyclin B- cdk1
what increases catalytic efficiency of CDK
phosphorylation on T160 by CDK activating kinase (CAK)
how do CDK inhibitor proteins work
they bind to and inactivate cyclin and CDK subunits
prevents phosphorylation
what actively degrades the cyclins once their function is complete
the proteosome
what cyclin-CDK complexes regulate G1/S phase
cyclin E-CDK2
