L04 - CONTROL OF CELL PROLIFERATION

Question 1

How does a cell regulate cell division? (3 things)

Answer 1

• Growth factor signalling
• Cell- cell communication - can stimulate division and inhibit division
• Checkpoints - tell whether or not to proceed

Question 2

Why is it important to regulate the cell cycle?

Answer 2

Important so that the body can ensure that daughter cells are genetically identical to the

Question 3

What happens during G1?

Answer 3

• Growth of cytoplasm
• Number of organelles increases
• Preparation for cell to divide

Question 4

What does the G1 checkpoint check?

Answer 4

• Does the cell have enough nutrients to divide?
• Is the extracellular environment suitable for cell division?
• Is there enough growth factor?

Question 5

When do environmental/ extracellular factors affect cell division?

Answer 5

During G1 and before the destruction point which occurs after the G1 checkpoint

Question 6

What does the G2/S checkpoint check?

Answer 6

• DNA integrity
• Has DNA replicated successfully and without any damages, if so have the damages been repaired
• Has all of the DNA been replicated

Question 7

What does the mitosis (M phase) checkpoint check?

Answer 7

Checks that centromeres centromeres are split correctly and that one chromatid is at each end of the spindle fibre - this ensures that daughter cells are equal and identical.

Question 8

What is the normal state for most cells?

Answer 8

G0 - no cell division occurring

Question 9

What does cdk stand for, and what do they do?

Answer 9

• Cyclin dependant Kinases
• Regulate the transition from one checkpoint to another
• Different Cdk’s at each checkpoint

Question 10

What is a kinase?

Answer 10

An enzyme that activates/ deactivates a protein by phosphorylating them

Question 11

How do you activate or deactivate a protein?

Answer 11

Phosphorylate the protein using a kinase

Question 12

How do you activate a kinase?

Answer 12

Bind the kinase to a cyclin molecule - hence the name cyclin dependant kinases