3.8.2 Gene Expression continued Flashcards
1
Q
What are oncogenes?
A
- occur when proto-oncogenes mutate and become oncogenes
- oncogenes are switched on permanently and stimulate the cell to divide continually
2
Q
What are the 2 ways oncogenes can work?
A
- produce faulty cell surface receptors that are continuously switched on so always activate cell division
- cause production of large amounts of growth factor which stimulate other cells to divide continuously
3
Q
How can oncogenes be activated?
A
Hypomethylation of the oncogene (methyl group removed), activates gene
4
Q
What are tumour suppressor genes?
A
- slow down cell division
- tells cells to undergo apoptosis
- if inactivated, they are switched off so can cause cancer (can’t tell cells to stop cell division)
5
Q
What is apoptosis?
A
Programmed cell death
6
Q
How can tumour suppressor genes be inactivated?
A
- hypermethylation (methyl groups added to cytosines)
- at the promoter region of the tumour suppressor gene
- inhibits transcription
- tumour suppressor gene is switched off
- increased rate of uncontrolled cell division
7
Q
(Extra) example of tumour suppressor gene
A
- TP53 gene produces P53 protein, which is involved in apoptosis
- if not produced, the faulty cells don’t undergo apoptosis
8
Q
(Extra) example of cancer caused by hypermethylation
A
- breast cancer
- hypermethylation of BRCA1
9
Q
Benign tumours
A
- slow growing
- cells produce adhesion chemicals so stick together
- tumour surrounded by a capsule
- does not cause cancer and does not invade other tissues causing damage
- no metastasis (doesn’t start new tumours elsewhere in body)
- can be removed with surgery
10
Q
What are malignant tumours?
A
- mass of undifferentiated and unspecialised cells
- higher rate of uncontrollable cell divison
- cells don’t stick together (no adhesion chemicals produced) so can spread to other parts of the body
- metastasis- cells can break off and form new tumours
- tumour not surrounded by a capsule
- need chemotherapy and radiotherapy to remove
