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The Cell Cycle

Problems

Cell Cycle Regulation

How to Cite This SparkNote

Problem : What class of molecules are responsible for regulating the cell cycle?

The regulators of the cell cycle are proteins.

Problem : What are the two classes of regulatory proteins discussed in this section?

Cyclin-dependent protein kinases and cyclins.

Problem : Why do cyclins have their name?

Cyclins are called such because they undergo a constant cycle of synthesis and degradation. These changes signal cell cycle phase shifts.

Problem : Fill in the blanks: _________ binds to cyclin-dependent protein kinases (Cdks) to activate them. Once activated, Cdks signal progression through the cell cycle through _________, a process in which phosphate groups are added to other molecules.

Cyclins. Phosphorylation.

Problem : What is the name of the complex formed when mitotic cyclins bind to Cdks and what is the role of this complex?

Activation of M-phase- promoting factor (MPF) is responsible for signaling the entrance into M phase. Its deactivation signals the exit from M phase.

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