Question

As part of the cell cycle control system, the progression through stages can be affected by the concentration of the ________ proteins, whose presence activate certain regulatory proteins to initiate major events in the cycle.

Answer 1

Answer: cyclin

As part of the cell cycle control system, the progression through stages can be affected by the concentration of the cyclin proteins, whose presence activate certain regulatory proteins to initiate major events in the cycle.

Explanation:

Cyclin refers to a family of related proteins which controls the cell cycle progression. This changing concentraion activates or deactivates the cyclin-dependent kinase (CDK) enzymes that are required for cell cycle. The concentration of various cyclins vary through the different stages of cell cycle, thereby regulating it. Cdk itself is in its inactive form. When cyclin binds to Cdk, it activates it. The activaed Cdk phosphorylates various target proteins that are associated with cell cycle.

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