Cell Cycle Checkpoints: Mechanisms and Importance in Cell Division

The video provides a detailed explanation of cell cycle checkpoints, focusing on the G1-S, G2-M, and M phase checkpoints. It describes how cells assess their environment and DNA integrity before proceeding with division. The G1-S checkpoint involves DNA damage sensors like ATM and ATR, which activate P53 to pause the cycle for repair. The G2-M checkpoint ensures DNA replication is complete and undamaged before mitosis. The M phase checkpoint ensures proper chromosome alignment and tension before segregation. The video references 'Molecular Biology of the Cell' by Harvey Lodish for further reading.

What are the three main checkpoints in the cell cycle discussed in the video?

• G1-S transition, G2-M transition, and M phase

• G1-S transition, G2-S transition, and M phase

• G1-S transition, S-G2 transition, and M phase

• G1-G2 transition, G2-M transition, and S phase

What is the primary function of the G1-S transition checkpoint?

• To repair DNA damage during mitosis

• To initiate cell division

• To assess the cell's environment and DNA integrity

• To ensure proper chromosome alignment

Which protein is phosphorylated by Check 2 kinase during the G1-S checkpoint?

• Cyclin D

• P21

• P53

• MDM2

What happens if DNA damage is irreparable at the G1-S checkpoint?

• The cell proceeds to S phase

• The cell undergoes apoptosis

• The cell repairs the damage and continues

• The cell enters G0 phase

What does the G2-M checkpoint primarily check for?

• Cell size and nutrient availability

• Completion of cytokinesis

• DNA damage and unreplicated DNA

• Proper chromosome alignment

Which complex is inhibited by Check 1 kinase during the G2-M checkpoint?

• Cyclin A-CDK2

• Cyclin B-CDK1

• Cyclin E-CDK2

• Cyclin D-CDK4

What is the role of MAD proteins in the M phase checkpoint?

• To degrade securin

• To promote DNA replication

• To inhibit APC and prevent premature chromosome separation

• To activate separase

What ensures proper chromosome alignment during the M phase checkpoint?

• Tension sensors at the kinetochore

• DNA polymerase

• P53 activation

• Cyclin B-CDK1 complex

What happens if there is unequal tension during the M phase checkpoint?

• The cell enters G0 phase

• The cell undergoes apoptosis

• The cell cycle is paused until tension is normalized

• Chromosomes are immediately separated

Which book is recommended for further reading on cell cycle checkpoints?

• Biology by Campbell and Reece

• Molecular Biology of the Cell by Harvey Lodish

• Molecular Cell Biology by Lodish et al.

• The Cell: A Molecular Approach by Geoffrey Cooper