Cell Cycle Control

The video explains the regulation of the cell cycle, highlighting two key checkpoints: between the G1 and S phases, and between G2 and mitosis. Cyclin-dependent kinases (CDKs) play a crucial role in this regulation, requiring activation by specific cyclins produced at different stages. The video details how CDKs, when activated by cyclins, phosphorylate proteins to either promote or inhibit processes like DNA replication and mitosis. Understanding these mechanisms is essential for comprehending how cells control their division and replication.

What are the two main checkpoints in the cell cycle?

• Between G1 and G2, and between S phase and mitosis

• Between G2 and S phase, and between mitosis and G1

• Between S phase and G2, and between mitosis and cytokinesis

• Between G1 and S phase, and between G2 and mitosis

What is the primary function of cyclin-dependent kinases (CDKs)?

• To degrade cyclins

• To add phosphate groups to proteins

• To remove phosphate groups from proteins

• To synthesize DNA

How are CDKs activated?

• By binding to specific cyclins

• By being degraded

• By binding to DNA

• By being phosphorylated

Which cyclins are produced during the G1 phase?

• Cyclins C and D

• Cyclins D and E

• Cyclins A and B

• Cyclins E and F

What is the role of the CDK-4 cyclin D complex?

• To activate mitosis

• To degrade cyclin E

• To phosphorylate the RB protein

• To inhibit DNA replication

What happens when RB protein is phosphorylated?

• It inhibits DNA replication

• It degrades cyclin D

• It activates mitosis

• It becomes inactive

During which phase is cyclin A produced?

• Mitosis

• G2 phase

• S phase

• G1 phase

What is the function of the cyclin B CDK-1 complex?

• To degrade cyclin A

• To activate DNA replication

• To inhibit mitosis

• To activate mitosis

Why is it important to have cyclin proteins present at checkpoints?

• To remove phosphate groups from proteins

• To inhibit proteins blocking DNA synthesis

• To degrade CDKs

• To synthesize new DNA

Which phase involves the production of cyclin B?

• Mitosis

• G2 phase

• S phase

• G1 phase