Control Of The Cycle Flashcards
What is controlled by checkpoints
Progression through the cell cycle
What are checkpoints
Mechanisms within the cell that assess the condition of the cell during the cell cycle and half progression to the next phase until certain requirements are met.
What is involved in regulating the cell cycle
Cyclin proteins that accumulate during cell growth
What do cyclins do
Combine with and activate cyclin-dependent kinases.
What do active cyclin-CDK complexes do
Phosphorylate proteins that regulate progression through the cycle. If sufficient phosphorylation is reached, progression occurs.
At the G1 checkpoint what does retinoblastoma proteins act as
A tumour surpressor by inhibiting the transcription of genes that code for proteins needed for DNA replication.
What does phosphorylation by G1 cyclin-CDK do
Inhibits the retinoblastoma protein. This allows transcription of the genes that code for proteins needed for DNA replication so cells progress from G1 to S phase
What happens at the G2 checkpoint
The success of DNA replication and any damage to DNA is assessed
What does DNA damage do
Triggers the activation of several proteins including P53.
What can p53 do
Arrest the cell cycle or cause cell death
What does a metaphase checkpoint control
The progression from metaphase to anaphase
What happens in metaphase
Progression is halted until the bromoformes are aligned correctly on the metaphase plate and attached to the spindle microtubules
What results in degenerative diseases
An uncontrolled reduction in the rate of the cell cycle
What may result in tumour formation
An uncontrolled increases in the rate of the cell cycle
What’s 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
