AP BIOLOGY

CELL DIVISION

THE CELL CYCLE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
A type of CdK-cyclin complex that promotes mitosis and peaks in concentration at the end of mitosis.
A
p53
B
RAS gene
C
Platelet Derived Growth Factor (PDGF)
D
Maturation (Mitosis) Promoting Factor (MPF)
Explanation: 

Detailed explanation-1: -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-2: -Cyclin-dependent kinase 1 (CDK1) is the enzymatic subunit of M-phase Promoting Factor (MPF). It is positively regulated by phosphorylation on Thr-161 and association with a cyclin B molecule.

Detailed explanation-3: -The cyclin A/CDK2 complex terminates the S phase by phosphorylating CDC6 and E2F1, and drives the cell-cycle transition from S phase to G2 phase, and subsequently activates CDK1 by cyclin A leading the cells to enter the transition to M phase. Upon mitosis, CDK1 activity is maintained by the complex cyclin B/CDK1.

Detailed explanation-4: -Maturation-promoting factor (MPF) MPF provides a good example of how cyclins and Cdks can work together to drive a cell cycle transition. Like a typical cyclin, M cyclin stays at low levels for much of the cell cycle, but builds up as the cell approaches the G 2start subscript, 2, end subscript/M transition.

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