Cell Cycle Regulation: Cyclins and CDKs Explained

The video explains the importance of cell cycle regulation, highlighting the roles of cyclins, CDKs, and tumor suppressors in controlling cell growth. It details the function of cyclins and CDKs at various checkpoints, focusing on cyclin D, E, and A in the G1, S, and M phases. Cyclin A is crucial for DNA replication and mitosis, while cyclin B is essential for mitotic exit. The video emphasizes the need for precise regulation to prevent uncontrolled cell division or failure to divide.

Why is cell cycle regulation crucial?

• To prevent cells from ever multiplying

• To control cell growth and prevent mass formation

• To allow cells to grow indefinitely

• To ensure cells multiply non-stop

Tags

NGSS.HS-LS1-4

What mediates progression through cell cycle checkpoints?

• Only CDKs

• Only tumor suppressors

• Only Cyclins

• Cyclins, CDKs, and tumor suppressors

What is the role of Cyclin D in the cell cycle?

• It drives the G1/S phase transition

• It initiates mitosis

• It degrades p27 kip one

• It terminates DNA replication

Tags

NGSS.HS-LS1-4

Which complex fully phosphorylates RB?

• Cyclin D/CDK4

• Cyclin E/CDK2

• Cyclin A/CDK1

• Cyclin B/CDK1

What happens when Cyclin A associates with CDK2?

• The cell exits mitosis

• The cell enters G1 phase

• The cell enters S phase

• The cell enters M phase

Tags

NGSS.HS-LS1-4

How does Cyclin A ensure DNA replication occurs only once per cell cycle?

• By phosphorylating RB

• By degrading Cyclin E

• By preventing assembly of excessive replication complexes

• By initiating assembly of the pre-replication complex

What is the role of Cyclin B in mitosis?

• To phosphorylate p27 kip one

• To degrade Cyclin A

• To form the maturation promoting factor (MPF)

• To initiate DNA replication

Tags

NGSS.HS-LS1-4

What happens to the concentration of MPF during mitosis?

• It falls gradually

• It rises until mitosis and then falls abruptly

• It decreases gradually

• It remains constant

Tags

NGSS.HS-LS1-4

Which Cyclin-CDK complex is necessary for cells to enter M phase?

• Cyclin D/CDK4

• Cyclin E/CDK2

• Cyclin A/CDK2

• Cyclin B/CDK1

Tags

NGSS.HS-LS1-4

What is the function of Cyclin A/CDK1 complex in G2 phase?

• To phosphorylate RB

• To initiate DNA replication

• To stabilize Cyclin B/CDK1 complex

• To degrade Cyclin D

Tags

NGSS.HS-LS1-4