Gene Expression- Cancer

Question 1

What are acquired mutations?

Answer 1

Mutations that occur in individual cells after fertilisation

Question 2

How can uncontrolled cell division be caused?

Answer 2

If these mutations occur in the genes that control the rate of cell division

Question 3

What is a tumour?

Answer 3

A mass of abnormal cells

Question 4

What are cancers?

Answer 4

Tumours that invade and destroy surrounding tissue

Question 5

What are the two types of genes that control cell division?

Answer 5

Tumour suppressor genes and proto-oncogenes

Question 6

What can mutations in tumour suppressor genes and proto-oncogenes cause?

Answer 6

Cancer

Question 7

Why are tumour suppressor genes inactivated?

Answer 7

If a mutation occurs in the DNA sequence

Question 8

What do tumour suppressor genes do when functioning normally?

Answer 8

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

Question 9

What happens if a mutation occurs in a tumour suppressor gene?

Answer 9

The protein isn’t produced and the cells divide uncontrollably (the rate of division increases) resulting in a tumour

Question 10

How can the effect of a proto-oncogene be increased?

Answer 10

If a mutation occurs in the DNA sequence

Question 11

What is an oncogene?

Answer 11

A mutated proto-oncogene

Question 12

What do proto-oncogenes do when functioning normally?

Answer 12

Stimulate cell division by producing proteins that make cells divide

Question 13

What happens when a mutation occurs in a proto-oncogene?

Answer 13

The gene becomes overactive which stimulates cells to divide uncontrollably (rate of division increases) resulting in a tumour

Question 14

What are the two different types of tumour?

Answer 14

Malignant and benign

Question 15

What are malignant tumours?

Answer 15

Cancers that usually grow rapidly and invade and destroy surrounding tissues- cells can break off the tumours and spread to other parts of the body in the bloodstream or lymphatic system

Question 16

What are benign tumours?

Answer 16

Not cancerous that usually grow slower than malignant tumours and are often covered in fibrous tissue that stops cells invading other tissues- often harmless but can cause blockages and put pressure on organs, can become malignant

Question 17

What are the 6 ways tumour cells can differ from normal cells?

Answer 17

• Irregular shape
• Nucleus is larger and darker or may have more than one nucleus
• Don’t produce all the proteins needed to function correctly
• Have different antigens on surface
• Don’t respond to growth regulating processes
• Divide more frequently

Question 18

What does methylation work?

Answer 18

Adding a methyl group onto something

Question 19

How is methylation of DNA an important method of regulating gene expression?

Answer 19

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

Question 20

When does methylation become a problem?

Answer 20

When it happens too much (hypERmethylation) or too little (hypOmethylation)

Question 21

What can abnormal methylation of certain cancer-related genes cause?

Answer 21

The growth of tumours

Question 22

What does hypERmethylation of tumour suppressor genes cause?

Answer 22

Genes not being transcribed so the proteins they produce to slow cell division aren’t made- means the cells are able to divide uncontrollably by mitosis and tumours can develop

Question 23

What does hypOmethylation of proto-oncogenes cause?

Answer 23

Them to act as oncogenes to increase the production of proteins that encourage cell division- stimulates cells to divide uncontrollably to cause the formation of tumours

Question 24

What is increased exposure to oestrogen thought to cause?

Answer 24

Increase a woman’s risk of developing breast cancer

Question 25

What are the 3 reasons that oestrogen may contribute to development of breast cancer?

Answer 25

• Oestrogen can stimulate certain breast cells to divide and replicate- more cell divisions are taking place naturally increases chance of mutations occurring so increases chance of cells becoming cancerous
• Ability to stimulate division could also mean that if cells do become cancerous, rapid replication could be further assisted by oestrogen to help tumours form quickly
• Research suggests that oestrogen is actually able to introduce mutations directly into DNA of certain breast cells which again increases risk of cells becoming cancerous