Cell researchers are investigating the role of cyclins on mitosis and cell division. They notice that cyclins build up, cause the cell to progress through the cell cycle, then break down, thus ending the different stages of the cell cycle. A failure of the cell to break down which cyclin would most directly lead to increased cell division? A) Cyclin A
B) Cyclin B
C) Cyclin D
D) Cyclin E

Cell researchers are investigating the role of cyclins on mitosis and cell division. They notice that cyclins build up, cause the cell to progress through the cell cycle, then break down, thus ending the different stages of the cell cycle. A failure of the cell to break down which cyclin would most directly lead to increased cell division?

A) Cyclin A

B) Cyclin B

C) Cyclin D

D) Cyclin E

The answer is: M-phase cyclins form M-CDK complexes and drive the cell's entry into mitosis; G1 cyclins form G1-CDK complexes and guide the cell's progress through the G1 phase; and so on. ... Specific enzymes break down cyclins at defined times in the cell cycle. When cyclin levels decrease, the corresponding CDKs become inactive.