6 Cells divide and multiply in number as they proceed throug

6. .Cells divide and multiply in number as they proceed through the cell cycle. At some point however cells need to stop multiplying and the cell cycle is halted. Given your knowledge on mitosis think of two ways (methods, mechanisms procedures) a cell might stop it self from dividing.

7. What are the implications for an organism that can not stop mitosis

Solution

6. Normal cells move through the cell cycle in a regulated way and cells use cues from the environment around them to decide whether to proceed with cell division. This regulation makes sure that cells don\'t divide under unfavourable conditions.

There are a number of checkpoints but the three most important ones are

a. The G1 checkpoint at G1/S transition: Main decision point for a cell, once the cell passes the G1 checkpoint and enters S phase, it becomes irreversibly committed to the division. During this cell checks for cell size, nutrients, growth factors and DNA damage.

b. The G2 checkpoint at the G2/M transition: To make the cell division smooth the cell has an additional checkpoint before M phase. It checks for the DNA integrity, DNA replication.

c. The spindle checkpoint at a metaphase to anaphase transition.

7. When an organism can not stop mitosis it leads to uncontrollable division of cells which ultimately leads to development of cancer