6. Oncogenes and tumour suppressors

Question 1

What sort of gene is Ras?

Answer 1

Proto-oncogene

Question 2

Recall 2 genotypes of the Ras oncogene and the effect they have

Answer 2

V12Ras - inhibits GAP binding

L61Ras - permanently GTP-bound

Question 3

What is a chimeric gene?

Answer 3

Gene produced by translocation

Question 4

Recall the translocation that produces the Philadelphia chromosome

Answer 4

ABL on C9

BCR on C22

Question 5

What sort of cancer is caused by the Philadelphia chromosome?

Answer 5

CML

Question 6

How might the G1 checkpoint of a cell be overridden?

Answer 6

Permanent activation of a cyclin

Question 7

What sort of gene is retinoblastoma?

Answer 7

Tumour suppressor

Question 8

What sort of gene mutation is associated with early-onset disease states?

Answer 8

Tumour suppressor mutation

Question 9

Recall the locus of the retinoblastoma gene

Answer 9

C13q14

Question 10

Describe the control of P53

Answer 10

It can be rapidly degraded when it is stable

It is destabilised by phosphorylation, which slows it degradation and allows it to exert its effects

Question 11

Recall the protein-binding of P53

Answer 11

When inactive, bind MDM2

Question 12

Recall the locus of the APC gene

Answer 12

5q21

Question 13

What sort of gene is APC?

Answer 13

Tumour suppressor gene

Question 14

What is the function of the gene product of APC?

Answer 14

Alters transcription via the WNT pathway

Controls beta-catenin activity

Question 15

Recall a common mutation associated with polyp progression to malignant adenoma?

Answer 15

K-Ras

Question 16

Recall the 3 subsequent mutations that are commonly seen in colorectal cancer

Answer 16

APC
K-Ras
P53