Mitosis checkpoints?

Question

what are the checkpoints for the G1 phase and the M phase? What are protein kinases? Can you give me an example of "Cyclin dependent kinases?"

Answer 1

A checkpoint in the cell cycle is a critical point where stop and go-ahead signals can regulate the cycle. Three major checkpoints are found in the G1, G2 and M phases.

The G1 checkpoint ("restriction point") is the most important checkpoint. If a cell receives a go-ahead signal at the G1 checkpoint, it will usually complete the S, G2 and M phases and divide. Alternatively If it does not receive a go-ahead signal at that point, it will exit the cycle, switching into a nondividing state called the G0 phase.

Protein kinases are enzymes that transfer phosphate groups from ATP to a protein.

Cyclin-dependent kinases are protein kinases that are active only when attached to a particular cyclin (hence the term "cyclin-dependent"). An example of a cyclin-cdk complex is the MPF (maturation-promoting factor or "M-phase promoting factor").

hope i helped =)