cancer

Question 1

how does cancer form?

Answer 1

cancer is a result of mtuations to the genes which regulate mitosis

if a mutation occurs, a non functional protein is produced
mitosis is not regulated so the cells divide uncontrollably to form a tumour

Question 2

what are the 2 types of tumours?

Answer 2

benign and malignant

benign- non cancerous
malignant- cancerous

Question 3

benign tumours

Answer 3

grow very large but grow very slowly
non cancerous as produce adhesion molecules so they stick together and to the tissue
surrounded by a capsule so compact

can be removed by surgery
do not usually return

impact is localised and not life theratening but depends on location

Question 4

malignant tumours

Answer 4

grow very large very quickly
cancerous as do not produce adhesive molecules so metastasis occurs- break off the tissue and project into surrounding tissues, developing their own blood supply

cell nucleus becomes very large
cell becomes unspecialised again

life threatening
requires supplementary treatment e.g. chemotherapy or radiotherapy

higher risk of reoccurence.

Question 5

what causes tumours?

Answer 5

mutations to tumour suppressor genes and oncogenes
abnormal methylation of tumour suppressor genes and oncogenes
increase in oestrogen concentration

Question 6

oncogenes

Answer 6

oncogenes are mutated versions of the proto onco gene which intiates DNA replication and mitosis when the body needs new cells.

oncogenes cause this process to be permanently activated and cells divide continually.

Question 7

mutation to tumour suppressor gene

Answer 7

tumour suppressor genes produce proteins which reduce cell division and destroy cells which have DNA replication issues.

if the tumour suppressor gene does not produce this protein, this process does not occur and cells continually divide
mutated cells not identified and destroyed.

BRCAI and BRC12 are 2 tumour suppressor genes linked to breast cancer.

Question 8

methylation
hypomethylation of oncogenes
hypermethylation of tumour suppressor genes

Answer 8

hypermethylation of tumour suppressor genes
more methyl groups attached
gene inactivated/switched off permanently

hypomethylation of oncogenes
fewer methyl groups attached
gene activated/turned on.

Question 9

increased oestrogen concentration leading to breast cancer

Answer 9

the ovaries produce oestrogen to regulate the menstrual cycle.
this stops once women reach the menopause

instead, the fat tissue in the breast produces oestrogen
linked to causing breast cancer in post menopause women

knock on effect as tumour causes more oestrogen to be produced so tumour becomes bigger
attracts white blood cells so tumour increases in size even more

may be because oestrogen binds to gene and activates it
this is a gene that initiates transcription/ if it is a proto oncogene it is permanently activated and cells continually divide.