11.4 Regulation of the cell cycle Flashcards
do smaller or larger cells have a harder time dividing and are prone to dying
smaller cells
what must happen before a cell can leave G1
- enough enzymes to carry out functions
- presence of a signal
- enough nucleotides
- Need ATP from nutrients
- DNA intact
Why are early animal embryos useful models for studying cell cycle control?
because they are large and undergo many rapid mitotic cell divisions following fertilization.
Which enzymes become active and inactive in cell cycles?
kinases, proteins that phosphorylate other proteins
What is a cyclin?
regulatory proteins thats levels rise and fall with each turn of the cell cycle.
what do kinases do once activated by cyclins?
kinases phosphorylate target proteins involved in promoting cell division.
Where are CDK’s found and when are they activated?
always present within a cell but only active when bound to an appropriate cyclin
What triggers the the required cell cycle of events?
The kinase activity of the cyclin CDK complex
The clinical change in cyclin CDK activity depends on the
clinical levels of cyclins.
cyclin may be synthesized in response to
signalling pathways that promote cell division.
What are the 2 steps that occur during CDK activation?
- cyclins bind to inactive cyclin-dependent kinases to control progression through the cell cycle.
- CDK’s phosphorylate target proteins involved in promoting cell division.
How do CDK’s regulate proteins?
by phosphorylating them.
What are the 3 cyclin-CDK regulated transition stages?
G1/s cyclin-CDK
S cyclin-CDK
M cyclin-CDK
What occurs during G1/s cyclin-CDK?
necessary for cell to enter S phase. Prepares cell for DNA replication
What occurs during S cyclin-CDK?
necessary for cell to initiate DNA synthesis. Activates enzymes and other proteins necessary for DNA replication. S-cyclin CDK activity prevents the replication of proteins from reassembling at the same place and re-replicating the DNA
