Question

5. What features do mismatch repair, base-excision repair, and nucleotide-excision repair have in common? Help now, homework due tomorrow!

Answer 1

Mismatch repair, base excision repair, and nucleotide excision repair all result in the removal of nucleotides from DNA. All repair mechanisms that excise nucleotides share a common four-step pathway:
(1) DNA damage is detected.
(2) The damage is excised by DNA repair endonucleases.
(3) Following excision, DNA polymerase adds nucleotides to the free 3'–OH group, using the remaining strand as a template.
(4) Ligation of nicks in the sugar phosphate backbone by DNA ligase.