Molecular control of cell cycle Flashcards
what is cell growth
increase in cell number=proliferatio
and increased in cell size/mass/volume
What is the quiescent phase and why enter it
Go a) to differentiate
b) not enough nutrients so become stationary but still have proliferative potential
What are the stages of resuming the cell cycle
Competancy
re-entry
progression
What are competance factors
PDGF FGF ( platelet and fibroblast dervided), stimulate the cell to resume the cell cycle.
What maintains G0
TNFb
What is the restriction point
when the cell is commited to reentering the cell cycle
Name immediate early genes and stte their function
c-jun c-fos c-myc
transcription factors needed for normal cell cycle transit
activate delayed response genes, promote cell cycle progession
What does CDk1 activity depend on
Assocition with cyclin- b
phosphorylated state- inhibitory phosphorylation of tyrosines must be removed by phosphatase
activity of the cyclin dependant kinase inhibitors
What is the ultimate regulation
Proteolysis- removal of proteins by ubiquiatination, ubitquitin binds to a substrate, need 4 to mark it for removal
What are oncogenes
Promotors of tumour formation by positive regulation of cell cycle encoded by genes required for normal cell cycle progression.
The GF’s become what in the viral version
V-fos V-jun V-myc
What part of the growth signalling cascade can oncogenes become
Grwoth factors
receptors
intracelllular signalling molecules
transcription factors
What are tumour supressors
Negative regulators of the cell cycle, prevent progression
What tumour supressor genes are mutated in cancers
pRB in nearly all
p53 absent or inactivated in 50% of tumours, does not do anything unless there is a fault
