Cell cycle

How do cells determine wether to divide or not to divide? 
The way it determines to divide is by a signal to divide or not to divide.

What are the mechanics of the cell cycle and how is it controlled?
It is controlled by the proteins in the cell.

How does cancer develop? 
it develops when a cell decides to divide on its own without a signal to divide.

What roll do proto-oncogenes and tumor suppresser play in controlling the cell cycle?
The roll proto-oncogenes play is that they stimulate cell division and the accelerator.

How do cancer treatments work and why they are not good for the body?
 cancer treatments use high doses of radiation targeted at the cancer cells. The reason they are not good for the body is because of the radiation.

Why does a multicellular organism need to control and coordinate cell division?  
It needs to control and coordinate cell division because some cells don't need to divide all the time.

What might be the consequences of uncontrolled cell division in a multicellular organism?
The consequences of uncontrolled cell division in a multicellular organism is that it can cause mutation and the cells won't divide.

What does it mean when we say that there are several “checkpoints” that occur during the cell cycle?
it means that cells have to go through a process to be able to divide.

Give an example of an external signal that regulates cell division and explain how it works.
Internal controls: Protein molecules vary concentrations during the cell cycle.

Compare and contrast the functions of proto-oncogenes and tumor suppressor genes.Give an example of each and explain why mutations in these genes can lead to cancer.
Proto-oncogenes: stimulates cell division, go sign for the cell cycle, mutated cells always on.  

Proto-oncogenes can lead to cancer because the mutated genes will still be active and will keep on dividing.

Tumor suppressor genes: Inhibits cell division, the brake peddle of the cell cycle, keeps mutated cells off.

Tumor suppressor genes can lead to cancer because if it does not work properly it can cause it to grow out of control.