MG: lec 2

Question 1

What triggers the cell to proliferate?

Answer 1

mitogens (growth factors) which are secreted by other cells to operate within the target cel via a “signal transduction cascade”

Question 2

What happens to a cell that does not get triggered by mitogens to undergo mitosis?

Answer 2

It will enter G0, where the cell leaves the cell cycle and enters a mitotically-inactive state.

Question 3

What are the two types of G0 for cells?

Answer 3

1. the “quiescent” type: can return to the cell cycle if needed for replacement/ reparative growth
2. the terminally differentiated type: where the cell is irreversibly committed to a specialized function (can still grow in size)

Question 4

What are the phases of the cell cycle?

Answer 4

1. G1 phase
2. synthetic, S phase
3. G2 phase
4. M phase

Question 5

What is interphase?

Answer 5

G1, S, G2

Question 6

How many cells of the body are considered “arrested” in G1?

Answer 6

Majority are in G0 (in a mature body)

Question 7

Average duration of cell cycle

Answer 7

20 hours, M phase being 30 mins to 1 hour.