lecture 25 - cell cycle and control Flashcards
cyclin-dependent kinases
enzyme that activates or deactivate other proteins by phosphorylating them
what happens if a cell does not pass the G1 checkpoint?
it enters the G0 phase
G0 phase
non-dividing state
true or false - nerve and muscle cells do not divide at all
true
what do Cdks link with to become active?
cyclin
maturation promoting factor
triggers mitosis at the G2 checkpoint
what is maturation promoting factor composed of?
cyclin and cdk
how is maturation promoting factor produced?
cyclin dependent kinase binds with cyclin, which promotes mitosis
what does high cyclin level indicate?
maturation promoting factor activates
why can liver cells enter G1 checkpoint and G0 checkpoint?
liver cells might enter G0 but can re-enter the cell and divide again if the body signals it to (like during injury)
which stages does cyclin accumulate?
S and G2 phase
what happens during the M checkpoint?
ensures sister chromatids are properly attached to spindle fibres before anaphase
where are cell cycle regulatory molecules found?
cytoplasm
what are the two cell cycle regulatory molecules called?
CDK and cyclin
what phase does the cell enter if it can not divide?
G0 phase
what if M checkpoint fails?
damaged cells may undergo apoptosis
where does M checkpoint occur?
metaphase
what are the cell cycle checkpoints?
g1,g2,M
when does MPF turn off?
anaphase
what role does PDGF play in cell division?
heals wounds that are injured
density dependent inhibition
crowded cells stop dividing when they reach a certain density
what releases PDGF?
platlets
what is the role of MPF in the cell cycle?
initiates mitosis by triggering passage through the G2 checkpoint
