Topic 8A: Cancers

Question 1

How does cancers occur?

Answer 1

When mutation in genes cause an uncontrollable cell growth. This eventually forms tumours

Question 2

What are acquired mutations?

Answer 2

Mutations that occur in the individual cells after fertilisation

Question 3

What causes uncontrolled cell divisions?

Answer 3

When the mutations occur in the genes that control the rate of cell division

Question 4

What are tumours?

Answer 4

-a mass of abnormal cells

Question 5

How do you know the tumours are cancerous?

Answer 5

they invade and destroy surrounding tissues

Question 6

Name the types of genes that control cell division

Answer 6

• tumour suppressor genes

- proto-oncogenes

Question 7

What do tumour suppressor genes do when they function normally?

Answer 7

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

Question 8

What happens if the tumour suppressor genes are mutated in the DNA sequence?

Answer 8

• the genes get inactivated
• the protein to stop cells dividing isn’t produced
• therefore cells divide uncontrollably
• rate of cell division increases
• results in a tumour

Question 9

What do proto-oncogenes genes do when they function normally?

Answer 9

• the genes stimulate cell division

- by producing proteins that make cells divide

Question 10

What happens if the proto-oncogenes genes are mutated in the DNA sequence?

Answer 10

• the effect of proto oncogenes are increased
• gene becomes overeactive
• stimulates cells to divide uncontrollably
• rate of cell division increases
• results in a tumour

Question 11

What do you call a mutated proto oncogene?

Answer 11

oncogene

Question 12

What are the two types of tumours?

Answer 12

Benign

Malignant

Question 13

What are benign tumours?

Answer 13

• non cancerous tumours
• grow slower than malignant tumours
• often covered in fibrous tissue which stops cells invading other tissues
• can cause blockage and put pressure on organs

Question 14

Can benign tumours turn into malignant?

Answer 14

Yes

Question 15

What are malignant tumours?

Answer 15

• cancerous tumours
• grow rapidly
• invade and destroy surrounding tissues
• cells can break off the tumours and spread to other parts
• like bloodstream/lymphatic system

Question 16

How do tumour cells looks different to normal cells?

Answer 16

• irregular shape
• nucleus larger and darker
• sometimes more than one nucleus
• dont produce all the proteins needed
• different antigens on their surface
• they don’t respond to growth regulating processes
• divide more frequently

Question 17

What is methylation?

Answer 17

adding a methyl group on something

Question 18

Why is the methylation of DNA important?

Answer 18

Because it ca control whether or not a gene is transcribed (copied into mRNA) and translated (turned into protein)

Question 19

Abnormal methylation caused by

Answer 19

growht of tumours

Question 20

Tumour suppressor genes are….

Answer 20

HypERmethylated

Question 21

Proto oncogenes are

Answer 21

HypOmethylated

Question 22

What does hypermethylated tumour suppressor gene leads to?

Answer 22

• genes not transcribed
• proteins to slow cell division is not made
• cells divide uncontrollably by mitosis

Question 23

What does hypormethylated proto oncogene gene leads to?

Answer 23

• act as oncogenes

- increases production of proteins for cells to divide

Question 24

Increased exposure to oestrogen can….

Answer 24

increase a woman’s risk of developing breast cancer

Question 25

What causes the increase exposure to oestrogen?

Answer 25

• starting menstruation early than usual
• starting menopause later than usual
• result in taking oestrogen containing drugs such as HRT

Question 26

Outline theories on how oestrogen contribute to the development of some breast cancer…

Answer 26

1) -oestrogen can stimulate certain breast cells to divide and replicate
- the more cell divisions can increase the chance of cells becoming cancerous
2) oestrogen maybe actually able to introduce mutations directly into the DNA of certain breast cells.
- increase the chance of these cells becoming cancerous