Cancer

Question 1

what are the 2 types of genes that control cell division?

Answer 1

tumour suppressor genes
proto oncogene

Question 2

How does a mutation in tumour suppressor genes cause cancer?

Answer 2

tumour suppressor gene can become inactivates if a mutation occurs
when functioning normally tumour suppressor genes slow cell division by producing proteins that stop cells from dividing or cause them to self destruct (apoptosis)
if mutation occurs, protein isn’t produced so cells able to divide uncontrollably and tumour formed

Question 3

how does a mutation of a proto-oncogene cause cancer

Answer 3

effect of proto-oncogene e can be increased if mutation occurs in DNA sequence
mutated proto-oncogene is called an oncogene
when functioning normally, proto-oncogenes stimulate cell division by producing proteins that make them divide
if mutation occurs in a proto-oncogene, the gene can be over-active, increasing rate of division, resulting in a tumour

Question 4

difference between benign and malignant

Answer 4

-malignant are cancerous, grow rapidly and destroy surrounding tissue, cells are not localised and can break off tumours and spread to other parts of body via bloodstream or lymphatic system (metastasis)

-benign tumours are not cancerous, glow slower, covered by fibrous tissue and encapsulated, localised cells, don’t invade other tissues, may put pressure on organs

Question 5

what does abnormal methylation cause

Answer 5

tumour growth

Question 6

hypermethylatiom

Answer 6

e.g. tumour suppressor genes are hypermethylated, genes are not transcribed, so proteins to slow cell division are not produced, cells continue to divide uncontrollably, tumour forms

Question 7

hypomethylation

Answer 7

e.g hypomethylation of proto-oncogenes causing them to act as oncogenes, increases production of protein that encourage cell division, cells divide uncontrollably, forms tumours

Question 8

effect of increased oestrogen

Answer 8

oestrogen can stimulate cells to divide, more cell divisions increase the change of a mutation, so increases chance of cell becoming cancerous

if cells do become cancerous, rapid replication can be stimulated further by oestrogen

oestrogen is also able to introduce mutations directly into the dna of breast cells