Controlling Checkpoints

Question 1

What are enzymes called that catalyse phosphorylation of proteins when activated?

Answer 1

Kinases

Question 1

What are the checkpoint proteins called that control cycles?

Answer 1

Cyclins

Question 2

What do these proteins do?

Answer 2

They cause the passing of a checkpoint

Question 3

How do these proteins maintain the cell cycle?

Answer 3

• Cyclins are activated when kinases bind to them forming complexes
• This changes specific cell cycle proteins in the cell, causing them to be activated
• When cyclin is not needed, enzymes break them down
• This breakdown signals the next stage in the cycle to occur
• Ensures DNA has replicated properly, the cell is the correct size and has enough nutrients

Question 4

What happens to a cell if irreversible damage occurs?

Answer 4

Apoptosis
- This prevents mutations from passing on to other cells

Question 5

What are the 2 types of control genes in a cell cycle?

Answer 5

• Proto-oncogenes
• Tumour suppressor genes

Question 6

What do proto-oncogenes do?

Answer 6

These produce proteins
Proteins act as signals that tell the cell if it needs to divide or if there is need for growth or repair

Question 7

What do tumour suppressor genes do?

Answer 7

If damage is detected or cell cycle is incorrectly completed, cell cycle will stop at the checkpoint
A mutation in this gene causes protein not to be made, allowing uncontrolled cell division

Question 8

How many checkpoints are there in a cell cycle?

Answer 8

3