3.8.2.3 Gene expression and cancer

Question 1

Tumor supressor genes

Answer 1

no or too little functional protein causes uncontrollable cell division

• can be inactivated by mutation - change in DNA base sequence meaning protein isn’t produced - gene is inactive
• or inactivated by hypermethylation - addition of CH3 stops TF/RNA polymerase binding

Question 2

Proto-oncogenes

Answer 2

too much protein production stimulates (mitosis) uncontrollable cell division

• mutation into oncogenes
• hypomethylation - too few CH3 attatched, too much transcription

Question 3

Benign tumour

Answer 3

• Non cancerous
• Slow growing
• Don’t spread - capsulated in fibrous tissue
• Normal cells

Question 4

Malignant tumour

Answer 4

• Cancerous
• Grow rapidly
• Invade and destroy surrounding tissues
• cells can break off and spread via bloodstream or lymphatic system
• Cells may have abnormal shape

Question 5

Why does increased oestrogen contribute to one cancers?

Answer 5

• Oestrogen stimulates cell division in breast tissue as it causes transcription of a proto-oncogene