Module 8 - Cancer

Question 1

What are mutations that occur after fertilisation called?

Answer 1

Acquired mutations

Question 2

How does cancer occur?

Answer 2

A mutation in a gene that controls the rate of cell division. If this causes uncontrollable cell division, this can result in a tumour which could be cancerous if it invades and destroys surrounding tissue

Question 3

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

Answer 3

Tumour suppressor genes and proto-oncogenes

Question 4

How do tumour suppressor genes work when functioning normally?

Answer 4

When functioning normally, tumour suppressor genes sow cell division by producing proteins that stop cells dividing or cause them to self destruct

Question 5

How can a mutation in the tumour suppressor genes lead to cancer?

Answer 5

If a mutation occurs in a tumour suppressor gene, the protein may not be produced. The cells will then divide uncontrollably resulting in a tumour

Question 6

How does a proto-oncogene work when functioning normally?

Answer 6

Proto-oncogenes stimulate cell division by producing proteins that that makes cells divide

Question 7

How does a mutation in the proto-oncogenes cause cancer?

Answer 7

If a mutation occurs, the gene can become overactive. This stimulates the cells to divide uncontrollably resulting in a tumour

Question 8

What are the two types of tumours?

Answer 8

Malignant and benign

Question 9

What are malignant tumours?

Answer 9

They usually grow rapidly and invade and destroy surrounding tissue. These cells can break off from the tumours and spread to other parts of the body in the bloodstream or lymphatic system - cancerous

Question 10

What are benign tumours?

Answer 10

These grow sower and are covered in fibrous tissue that stops the cells invading other tissue. They are non-cancerous but they can cause blockages and pressure on organs

Question 11

How do tumour cells differ to normal cells?

Answer 11

• They have an irregular shape
• The nucleus is larger and darker
  They don’t produce all the proteins needed to function correctly
• They have different antigens on their surface
• divide much more frequently

Question 12

What is methylation?

Answer 12

Adding a methyl group onto something and determines whether or not a gene is transcribed or translated

Question 13

What is the difference between hypermethylation and hypomethylation?

Answer 13

Hypermethylation - too much methylation
Hypomethylation - too little methylation

Question 14

What genes are hypermethylated?

Answer 14

Tumour suppressor genes

Question 15

How does hypermethylation lead to tumour growth?

Answer 15

When the tumour suppressor genes are hypermethylated, they genes are not transcribed so the proteins to slow cell division aren’t being made. This causes cells to divide uncontrollably and cause tumours to develop

Question 16

How does hypomethylation lead to the growth of tumours?

Answer 16

Hypomethylation of proto-oncogenes causes them to act as a oncogene - increasing the production of the proteins that encourage cell division. This stimulates cells to divide uncontrollably, causing the formation of tumours

Question 17

Explain how an increase in oestrogen can contribute to some breast cancers?

Answer 17

1) Oestrogen can stimulate some breast cells to divide and replicate, This increase in cell division increases the chances of mutations occuring, this means there is a higher chance of cells dividing more rapidly leading to tumours. If cells do become cancerous, the rapid replication could be further assisted by oestrogen, helping tumours form quickly.

Question 18

How are some drugs effective treatment of ER-positive breast cancers?

Answer 18

1. The drugs will bind to oestrogen receptors
2. This prevents the binding of oestrogen to the DNA binding site
3. Prevents the transcription factors binding to promoters reducing uncontrolled cell division