gene expression and cancer

Question 1

what is cancer

Answer 1

a group of diseases caused by damage to the genes that regulate mitosis and cell cycle leading to uncontrolled cell division and formation of a tumor

Question 2

why are benign less harmful

Answer 2

grow slowly do not spread easily as it sticks together and can be removed easily, normal nucleus formation

Question 3

why are malignant more harmful

Answer 3

rapidly divide and can break off and move to different parts of the body making it harder to remove and affect many functions

Question 4

what has dna analysis of tumours shown

Answer 4

in general cancer is derived from a single mutant cell

Question 5

what happens later

Answer 5

a further mutation in the descendant cell leads to other changes that cause subsequent cells to be different from normal

Question 6

what are the two genes that play a role in cancer

Answer 6

tumour supressor genes and oncogenes

Question 7

what are most oncogenes

Answer 7

mutation of proto-oncogenes

Question 8

what does protooncogenes do

Answer 8

they stimulate a cell to divide when growth factors they code attach to the protein on its cell surface membrane activating the genes that cause the DNA to replicate and cell divide

Question 9

what happens if a proto oncogene mutates to an oncogene

Answer 9

the genes is permanently switched on leads to excessive growth factors so growth receptors become permanently activated so cell division is excessive

Question 10

wht happens as a result

Answer 10

cells divide too rapidly and out of control and a tumour develops

Question 11

what are a few cancers caused by

Answer 11

inherited mutations of protooncogenes that cause oncogene to be activated

Question 12

what are tumour supressor gene

Answer 12

maintains rate of cell division and repairs mistakes in the DNA tell the cell when to carry out apoptosis maintain normal rates of cell division and prevent the formation of tumours

Question 13

what happens if a tumour supressor gene become mutated

Answer 13

it stops inhibiting cell division and damaged cells continue to divide rapidly out of control which may form a structurally different cell

Question 14

what happens to these cells

Answer 14

they survive and make clones of themselves and form tumours

Question 15

what are some cancers caused by

Answer 15

inherited mutations of the tumour supressor gene

Question 16

what is the difference between oncogenes and tumor supressor gene

Answer 16

oncogenes cause cancer when they bind and are activated

whilst tumor suppressor genes cause cancer when they are mutated and inactive

Question 17

how are cancers formed commonly in relation to tumour supressor genes

Answer 17

hypermethylation occurs in the promoter region of the tumor suppressor gene

Question 18

what does this lead to

Answer 18

the gene becoming inactivated so transcription is inhibited and gene switched off, lead to increased cell division and formation of a tumor

Question 19

what is hypomehtylation

Answer 19

reduced methylation

Question 20

how does it lead to cancer

Answer 20

the DNA is less compact and more exposed, so more accessible for transcription factors leading activation of oncogenes and uncontrolled cell division

Question 21

what role does oestrogen play

Answer 21

a role in regulating the menstrual cycle

Question 22

why does after menopause women breast cancer risk increase

Answer 22

as there is increased oestrogen concentration in the breasts

Question 23

what does localised oesstrogen concentration cause and lead to

Answer 23

trigger breast tumour and once tumour develops, it further increases oestrogen concentration which leads to development of tumour

Question 24

where can the oestrogen bind to

Answer 24

it can bind to the transcription factors that are specific to the protoncogenes which cause them to change to oncogene and leads to activation of this geen leading to rapid cell division