DNA Damage/Repair

Question 1

Name 4 exogenous sources of DNA damage

Answer 1

Ionising radiation
Alkylating agents
UV light
Anti cancer agents

Question 2

Name 3 endogenous sources of DNA damage

Answer 2

DNA replication errors
V(D)J recombination
Free radicals

Question 3

What factors can cause DNA replication stress? (3)

Answer 3

Defect in replication machinery e.g. Helicase, slippage

Replication fork blockage e.g. base excision repair defect causes SSBs to persist, RNA incorporation

Defects in response pathways e.g. Repair mechanisms, RNase H

Question 4

What is werner syndrome?

Answer 4

An autosomal recessive disease caused by mutations in the WRN gene which acts as a helicase. Leads to replication problems and DNA damage.

Question 5

What are the symptoms of Werner syndrome?

Answer 5

Patients display premature features of ageing - cataracts, skin ulcers, diabetes, cancer predisposition.

Question 6

What is p53?

Answer 6

“The guardian of the genome”
Is a tumour suppressor gene (involved in many aspects of DNA damage response)
Mutated in many cancers

Question 7

What is an oncogene?

Answer 7

A mutated form of a gene involved in normal cell growth. When mutated, often promote cancerous growth.