control of cell cycle Flashcards
rate of division too slow
degenerative disease Alzheimer
too fast
tumor formation
what is a checkpoint
a critical control point where stop and go signals regulate
if a go signal is not reached at the G1 checkpoint
the cell may be switched to a non-dividing state called G0
G1 checks 2
- cell size
- ensures sufficient mass to form 2 daughter cells
as the cell increases in G1
cyclin proteins accumulate
Cyclin bind with
regulatory proteins called Cdk Cyclin dependant kinases and activate them
Active Cdks cause
phosphorylation of proteins that stimulate the cell cycle
If sufficient threshold of phosphorylation is reached
the cell cycle moves on the next phase
if insufficient threshold is reached
the cell cycle is held at the G1 checkpoint
the G1 Cdk phosphorylate the transcription inhibitor
Retionoblastoma Rb allowing DNA replication in S to occur
Dna damage triggers the activation of several proteins including
p53, that stimulate
DNA repair
Arrest Cell cycle
Apoptosis
G1 / S is controlled by
p53 and Cdk
What is Retinoblastoma
a transcription inhibitor factor
Checkpoint during G2 (3)
- control entry to mitosis
- Checks DNA replication is correct
- so each daughter cell receives a complete genome
