Cancer

Question 1

What are tumour suppressor genes?

Answer 1

genes that produce proteins to slow cell division and cause cell death if DNA copying errors are detected

Question 2

What happens if a mutation occurs in tumour suppressor genes?

Answer 2

cell division will continue and mutated cells will not be detected and destroyed, cell division increases

Question 3

What is hypermethylation?

Answer 3

increased number of methyl groups added

Question 4

How might hypermethylation impact tumour suppressor genes?

Answer 4

cause them to tightly coil so would not be expressed (so it will not control mitosis or cause cell death)

Question 5

What is hypomethylation?

Answer 5

a decrease in the number of methyl groups added

Question 6

Why might hypomethylation lead to cancer?

Answer 6

oncogenes are turned on continually so mitosis is happening even when it is not needed

Question 7

What are proto-oncogenes?

Answer 7

genes that regulate the production of growth factors which stimulate cell division

Question 8

What are 3 roles of tumour Suppressor Genes?

Answer 8

• apostasis
• ‘fix’ DNA
• stop/reduce cell division

Question 9

What happens if tumour suppressor genes are mutated?

Answer 9

cell division increases due to less regulation

Question 10

What are mutated proto-oncogenes called?

Answer 10

oncogenes

Question 11

What are 2 ways that oncogenes cause increased cell division?

Answer 11

• increase the amount of growth factor produced
• stimulate growth factor receptors even when no growth factor is present

Question 12

How are malignant tumours different from benign tumours

Answer 12

malignant:
- grow fastER
- metastasise as no adhesion molecules produced
- are not surrounded by a capsule so grow into surrounding tissues
- more likely to be life-threatening
- often have systemic effects

Question 13

What is the role of adhesion molecules produced by benign tumours?

Answer 13

makes cells stick together so tumours do not metastasise

Question 14

How do tumours metastasise?

Answer 14

• develop blood and lymph vessels in vascularisation
• tumour cells enter blood or lymph vessels
• tumour cells circulate in blood/lymph
• tumour cells adhere to blood vessel walls, squeeze out and invade other tissues
• tumours also form in lymph nodes

Question 15

How does hypermethylation of tumour suppressor genes cause cancer?

Answer 15

• hypermethylation in promoter region of TSG
• TSG inactivated
• transcription inhibited
• increased, uncontrolled cell division