AP BIOLOGY

Detailed explanation-1: -MPF (“maturation-promoting factor” or “M-phase-promoting factor”) triggers the cell’s passage past the G2 checkpoint to the M phase. ○ MPF promotes mitosis by phosphorylating a variety of other protein kinases.

Detailed explanation-2: -How does MPF allow a cell to pass the G2 phase checkpoint and enter mitosis? A sufficient amount of MPF has to exist for the cell to pass the G2 checkpoint; this occurs through the accumulation of cyclin proteins which combine with Cdk to form MPF.

Detailed explanation-3: -In addition to driving the events of M phase, MPF also triggers its own destruction by activating the anaphase-promoting complex/cyclosome (APC/C), a protein complex that causes M cyclins to be destroyed starting in anaphase.

Detailed explanation-4: -MPF is activated at the end of G2 by a phosphatase, which removes an inhibitory phosphate group added earlier. The MPF is also called the M phase kinase because of its ability to phosphorylate target proteins at a specific point in the cell cycle and thus control their ability to function.

Detailed explanation-5: -CDK1 is a crucial regulator of mitotic transition and its activation drives entry into mitosis [4, 5]. MPF activity must be sustained from prophase to metaphase and subsequently turned off when cells enter anaphase.