3.8 The cell cycle

Question 1

When is the cell cycle implimented?

Answer 1

cells that do not divide continuously undergo a regular cell division separated by periods of growth.

Question 2

What are the 3 stages of the cell cycle and what do they involve?

Answer 2

1) INTERPHASE: no division takes place (resting phase) takes up 90% of the cycle.
2) NUCLEAR DIVISION: when the nucleus divides either into 2 (mitosis) or 4 (meiosis)
3) CYTOKINESIS: division of the cytoplasm to create new cells

Question 3

What is cancer?

Answer 3

• the uncontrolled growth and division of cells caused by damage to the genes that regulate mitosis and the cell cycle.
• this causes a group of abnormal cells to develop and constantly expand. only malignant tumors are cancerous.

Question 4

Why do cells divide by mitosis?

Answer 4

• either to increase the size of a tissue during development (growth) or to replace dead or worn out cells (repair)
• mitosis is controlled by 2 genes, and a mutation to either of these can result in uncontrolled mitosis.

Question 5

What is the difference between benign and malignant tumours?

Answer 5

• malignant tumours grow rapidly, are less compact, and can be lethal
• benign tumours grow slowly, are compact and not lethal

Question 6

how do cancer treatments work?

Answer 6

by blocking a part of the cell cycle and killing dividing cells so that the tumour growth ceases.

Question 7

How do drugs disrupt the cell cycle?

Answer 7

• prevents DNA from replicating

- inhibiting the metaphase by interfering with spindle fibre formation