1.5 Control Of The Cell Cycle Flashcards
Progression through the cell cycle is controlled by
Checkpoints
Define what a checkpoint is
Mechanisms within the cell that assess the condition of the cell during the cell cycle and halt progression to the next phase until certain requirements are met
What do active cyclin-CDK complexes do
Phosphorylate proteins that regulate progression through the cell cycle
If sufficient phosphorylation occurs, progression occurs
Cyclin proteins are accumulated during cell growth and are involved in the regulation of the cell cycle. What do they combine with and activate
Cyclin dependent kinases (cdks)
At the G1 checkpoint, the retinoblastoma protein acts as a tumor suppressor by doing what
Inhibiting the transcription of genes that code for proteins needed for DNA replication
What inhibits the retinoblastoma protein in the G1 checkpoint, and what does this allow
Cyclin-CDK
Transcription of the genes that code for proteins needed for DNA replication
So cells can progress from G1 to S phase
What does the G1 checkpoint check for
Cell size
Nutrients
Growth factors
Mechanical cues
DNA damage
What does the G2 checkpoint check for
The success of DNA replication
Damage to DNA is assessed
In the G2 checkpoint, what protein does DNA damage trigger the activation of, and what can this protein do
P53
Stimulate DNA repair, arrest the cell cycle or cause cell death
If the G2 checkpoint passes, the cell progresses to
The M phase
What does the metaphase checkpoint control
Progression from metaphase to anaphase
At the metaphase checkpoint, progression is halted until…
The chromosomes are aligned correctly on the metaphase plate and attached to spindle Microtubules
The metaphase checkpoint checks for
Chromosomes attachment to spindles at metaphase plate
An uncontrolled reduction in the rate of the cell cycle may result in
Degenerative disease eg Alzheimer’s disease
An uncontrolled increase in the cell cycle may result in
A tumor formation
