AP BIOLOGY

Detailed explanation-1: -For the cell to proceed through mitosis, MPF must be inactivated and other cyclins become active. This occurs through the destruction of cyclin M. During metaphase, MPF activates another protein complex called anaphase-promoting complex/cyclosome (APC/C).

Detailed explanation-2: -When the cyclin reaches a certain level, mitosis begins; and after mitosis the cyclin disappears.

Detailed explanation-3: -Maturation-promoting factor (abbreviated MPF, also called mitosis-promoting factor or M-Phase-promoting factor) is the cyclin-Cdk complex that was discovered first in frog eggs. It stimulates the mitotic and meiotic phases of the cell cycle.

Detailed explanation-4: -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-5: -Cyclin A, the founding member of the cyclin family of proteins, begins to accumulate in cells in late G1 phase, peaks in mid-G2 phase, and disappears completely at the beginning of mitosis (Sherr, 1994).