cancer

Question 1

when does it occur?

Answer 1

when the rate of cell multiplication is fatter than the rate of cell death
-> causes the growth of a tumour

caused by damage to DNA

Question 2

how can DNA get damaged?

Answer 2

physical factions like UV or asbestos

carcinogens ( chemicals ) - in environment or produced in cell metabolism

Question 3

if DNA is copied incorrectly in gamete formation, what can happen

Answer 3

a cancer can result

Question 4

what can abnormal methylation lead to?

Answer 4

abnormal methylation of genes in cancer cells can lead the the activation/ deactivation of genes in control of the cell cycle

Question 5

oncogenes

Answer 5

code for proteins that stimulate transition between stages in the cell cycle.
DNA mutations or epigenetic changes, such as less methylation, in these genes can lead to the cell cycle being continually active. this may cause excessive cell division, resulting in a tumour

Question 6

Tumour suppressor genes

Answer 6

produce suppressor proteins that stop the cycle. DNA mutations or epigenetic changes (ie more methylation inactivating these genes) mean there is no brake on the cell cycle

Question 7

tumour suppressor proton p53

Answer 7

inhibits enzymes at G1 /S
prevent cell from copying its DNA

In cancer cells a lot of this protein means the cell cannot stop entry into the S phase