DNA repair pathways

Question 1

The repair of O6-methylguanine back to guanine (carried out by O6-alkylguanine methyltransferase) is an example of which type of repair mechanism?

Answer 1

a) Direct reversal.
b) Mismatch repair.
c) Base excision repair.
d) Nucleotide excision repair.
e) Homologous recombination

Question 2

Which of the following statements about mismatch repair is FALSE?

Answer 2

a) MMR recognises single base-base mismatches.
b) MMR recognises insertions of deletions of one or more nucleotides.
c) MMR requires the MutS and MutL proteins.
d) Mutations in MMR proteins are linked to cancer phenotypes including hereditary non-polyposis colon cancer (HNPCC).
e) MMR involves the removal of just the single mismatched nucleotide.

Question 3

Which of the following statements about double strand break repair is TRUE?

Answer 3

a) Homologous recombination results in error-free repair.
b) Non-homologous end joining results in error-free repair.
c) The breast cancer associated BRCA1 and BRCA2 proteins are involved in non-homologous end joining.
d) Non-homologous end joining utilises the sister chromatid as template for the repair.
e) Homologous recombination repair requires Ku70, Ku80 and DNA-PK proteins.