8A 2. cancer

Question 1

uncontrolled cell growth can be caused by

Answer 1

mutations in genes

Question 2

mutations that occur in individual cells after fertilisation (e.g. in adulthood) are called

Answer 2

acquired mutations

Question 3

an acquired mutation in genes that control rate of cell division (by mitosis) can cause

Answer 3

uncontrolled cell division

Question 4

what results from uncontrollably dividing cells

Answer 4

a tumour (a mass of abnormal cells)

Question 5

tumours that invade and destroy surrounding tissue are called

Answer 5

cancers

Question 6

the two types of gene that control cell division

Answer 6

tumour suppressor genes and proto-oncogenes

Question 7

what do tumour suppressor genes do when functioning normally

Answer 7

slow cell division by producing proteins that stop cells dividing or cause them to self-destruct (apoptosis)

Question 8

what happens if a mutation occurs in a tumour suppressor gene

Answer 8

tumour supressor gene inactivated
protein isn’t produced
cells divide uncontrollably (rate of division increases)
resulting in a tumour

Question 9

what to proto-onco genes do when functioning normally

Answer 9

stimulate cell division by producing proteins that make cells divide

Question 10

what happens if a mutation occurs in a proto-oncogene

Answer 10

gene can become overactive
cells divide uncontrollably (rate of division increases)
resulting in a tumour

Question 11

what is a mutated proto-oncogene called

Answer 11

an oncogene

Question 12

what are the two types of cancer

Answer 12

benign

malignant

Question 13

features of malignant tumours

Answer 13

grow rapidly, invade and destroy surrounding tissue.

Question 14

how do malignant tumours spread

Answer 14

cells break off tumours and spread to other parts of the body in the blood stream or lymphatic system.

Question 15

are malignant tumours cancers?

Answer 15

yes

Question 16

features of benign tumours

Answer 16

grow slower

covered in fibrous tissue that stops cells invading other tissues

Question 17

are benign tumours cancers?

Answer 17

no but can become malignant

Question 18

do benign tumours cause harm?

Answer 18

often harmless HOWEVER can cause blockages and put pressure on organs.

Question 19

6 ways in which tumour cells differ from normal cells

Answer 19

1. irregular shape
2. nucleus larger and darker (sometimes ore than 1)
3. don’t produce all proteins needed to function correctly
4. different antigens on surface
5. don’t respond to growth regulating processes
6. divide by mitosis more frequently

Question 20

what does methylation mean

Answer 20

adding a methyl -CH3 group onto something

Question 21

how is methylation of DNA an important method of regulating gene expression

Answer 21

controls wether or not a gene is transcribed (copied into mRNA) and translated (turned into protein)

Question 22

hypermethylation is when

Answer 22

methylation happens too much

Question 23

hypomethylation is when

Answer 23

methylation happens too little

Question 24

abnormal methylation of certain cancer related genes can cause

Answer 24

growth of tumours

Question 25

what happens when tumour suppressor genes are hypermethylated

Answer 25

genes are not transcribed
proteins produced to slow cell division not made
cells divide uncontrollably by mitosis and tumours develop

Question 26

what happens when proto-oncogenes are hypomethylated

Answer 26

causes them to act as oncogenes
increased production of proteins that encourage cell division
cells divide uncontrollably by mitosis and tumours develop

Question 27

what is increased exposure to oestrogen is thought to do

Answer 27

increase womans risk of developing breast cancer

Question 28

2 THEORIES of how oestrogen can contribute to the development of some breast cancers

Answer 28

1. Oestrogen can stimulate certain breast cells to divide and replicate.
   more cell division = increased chance of mutations occurring = increased chance of cells becoming cancerous
   if cells become cancerous, rapid replication could be further assisted by oestrogen, helping tumours to form quickly.
2. Oestrogen can introduce mutations directly into DNA of certain breast cells = increased chance of cells becoming cancerous