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Question 14#

Which of the following is a regulator of the cell cycle?

A. CDK
B. Tyrosine kinase
C. Pol II holoenzyme
D. Caspase

Correct Answer is A

Comment:

The machinery that drives cell cycle progression is made up of a group of enzymes called CDKs. Cyclin expression fluctuates during the cell cycle, and cyclins are essential for CDK activities and form complexes with CDK. The cyclin A/CDKl and cyclin B/CDKl drive the progression for the M phase, while cyclin A/CDK2 is the primary S phase complex. Early G1 cyclin D/CDK4/6 or late Gl cyclin E/CDK2 controls the G1-S transition. There also are negative regulators for CDK termed CDK inhibitors, which inhibit the assembly or activity of the cyclin-CDK complex. Expression of cyclins and CDK inhibitors often is regulated by developmental and environmental factors.