Question

What regulates the cell growth cycle?

Answer 1

Cyclins and Cyclin Dependent Kinases (cdk's) determine a cell's progress through the cell growth cycle

Explanation:

Cycling are regulatory subunits with no catalytic activities.
Cdks are catalytic subunits which are inactive in absence of cyclins

Cyclins undergo constant cycle of synthesis and degradation during cell division. When Cyclins are synthesised they act as an activating protein and bind to cdks. This acts as a signal for the cell to pass on to the next cell cycle phase. Eventually the Cyclin degrades, deactivating the cdk.

There are two types of cyclins
A) mitotic cyclins
B) G1 cyclins

Regulation of cell cycle includes the detection and repair of genetic damage as well as the prevention of uncontrolled cell division. The molecular events that control the cell cycle are sequential and impossible to reverse.