Control Of The Cell Cycle Flashcards
What is progression through the cell cycle controlled by?
Checkpoints
What are checkpoints?
mechanisms within the cell that asses the condition of the cell during the cell cycle and halt progression to the next stage until certain requirements are met
What do cyclin proteins do?
Cyclin proteins that accumulate during cell growth are involved in regulating the cell cycle. Cyclins combine with and activate cyclin-dependent kinases (CDKs)
What does cyclin-CDK complexes do?
They phosphorylate proteins that regulate progression through the cycle. If sufficient phosphorylation is reached progression occurs
What happens at the G1 checkpoint?
Retinoblastoma protein (Rb) acts as a tumour suppressor by inhibiting the transcription of genes that code for proteins needed for DNA replication. Phosphorylation by G1 cyclin-CDK inhibits the Rb. This allows transcription of the genes that code for proteins needed for DNA replication. Then the cell progresses from G1 to S phase
What happens at the G2 checkpoint?
The success of DNA replication and any damage to DNA is assessed.
What can DNA damage trigger?
The activation of several proteins including p53 that can stimulate DNA repair or arrest the cell cycle or cause cell death
what does a metaphase checkpoint control?
The progression from metaphase to anaphase
What happens at the metaphase checkpoint?
Progression is halted until the chromosomes are aligned correctly on the metaphase plate and attached to the spindle microtubules
What may results in a degenerative disease?
An uncontrolled reduction in the rate of the cell cycle
What may result in tumour formation
An uncontrolled increase in the rate of the cell cycle
What is a proto-oncogene?
A normal gene usually involved in the control of cell growth or division which can mutate to form a tumour-promoting oncogene
