Cancer

Question 1

What are acquired mutations?

Answer 1

Mutations that occur in individual cells after fertilisation

Question 2

What is a tumour?

Answer 2

A mass of abnormal cells

Question 3

How can acquired mutations cause a tumour?

Answer 3

If they occur in the genes which control the rate of cell division, it can cause uncontrolled cell division

Question 4

What are cancers?

Answer 4

Tumours that invade and destroy surrounding tissue

Question 5

What two genes control the rate of cell division?

Answer 5

Tumour suppressor genes

Proto-oncogenes

Question 6

How does a tumour suppressor gene work?

Answer 6

Slows cell division by producing proteins that stop cells-dividing or cause them to self destruct

Question 7

What happens if there is an mutation in the tumour suppressor gene?

Answer 7

The gene will stop producing the proteins as the gene will become inactivated. The cells divide uncontrollably

Question 8

How does a proto-oncogene work?

Answer 8

They stimulate cell division by producing proteins that make cells divide

Question 9

What happens if there is a mutation in the proto-oncogene?

Answer 9

The gene will become overactive and stimulate cells to divide uncontrollably, resulting in a tumour

Question 10

What is a oncogene?

Answer 10

A mutated proto-oncogene

Question 11

What is apoptosis?

Answer 11

Programmed cell death which happens to cells that are infected, damaged or have reached the end of their functions life

Question 12

What are the two types of tumour?

Answer 12

Benign

Malignant

Question 13

What are malignant tumours?

Answer 13

Cancers

They grow rapidly and invade and destroy surrounding tissues

Question 14

What are benign tumours?

Answer 14

Not cancerous

They usually grow slower and are often covered in fibrous tissues that stop cells invading other tissues

Question 15

What can benign tumours sometimes become?

Answer 15

Malignant

Question 16

How are tumour cells different to normal cells?

Answer 16

• Their nucleus is larger and darker than normal cells
• They have an irregular shape
• They don’t produce all the proteins needed to function correctly
• They have different antigen on their surface
• They don’t respond to growth regulating processes
• They divide by mitosis more frequently than normal cells

Question 17

What are two of the causes of tumour growth?

Answer 17

Abnormal methylation

Exposure to oestrogen

Question 18

What is methylation?

Answer 18

Adding a methyl group to something -CH3

Question 19

Why is methylation of DNA important?

Answer 19

It can control whether or not a gene is transcribed and translated

Question 20

What is hypermethylation?

Answer 20

When methylation happens too much

Question 21

What is hypomethylation?

Answer 21

When methylation happens too little

Question 22

What happens when tumour suppressor genes are hypermethylated?

Answer 22

Their genes are not transcribed so the proteins they produce to slow cell division aren’t made

Question 23

What happens when a proto-oncogene is hypomethylated?

Answer 23

Causes them to act as oncogenes

Increases the production of the protein which encourages cell division

Question 24

Why is exposure to oestrogen thought to increase the chances of breast cancer?

Answer 24

• Stimulate certain breast cells to divide and replicate - more cell divisions increases the chance of mutations occurring
• If cells that replicate do become cancerous, their rapid replication can be further assisted by oestrogen
• Oestrogen is actually able to introduce mutations directly into the DNA of certain breast cells