Control Of Cell Divison ( Cancer Genes)

Question 1

How do Proto-oncogenes control the rate of cell division?

Answer 1

-They code for proteins which stimulate cell division by acting as growth factors

Question 2

How do Tumour suppressor genes control the rate of cell division?

Answer 2

They code for proteins which inhibit cell division

Question 3

What happens when a mutated tumour suppressor gene is produced?

Answer 3

1. Prevent the formation of a functional protein
2. So the protein can no longer inhibit mitosis
3. So the rate of mitosis increases

Question 4

Describe the impact of methylation of DNA on tumours.

Answer 4

1. Addition of methyl to DNA regulates gene expression; transcription and translation
2. Typically methylation inhibits transcription of genes
3. Abnormal methylation of cancer related genes can lead to the growth of tumours

Question 5

What is the role of oestrogen on breast cancer?

Answer 5

1. Oestrogen can stimulate certain breast cells to divide.
   —> an increase in oestrogen causes an increase in cell division so an increased chance of mutations occurring therefore increasing the chances of tumours forming
2. If cells become cancerous, high levels of oestrogen will cause the cancer cells division to increase further, which may cause tumours to grow quicker.
3. Other research suggests that oestrogen can introduce mutation directly in DNA of certain breast cells which increases the chance of these cells becoming cancerous