Question

Mutations or breaks in genomic DNA can be repaired in different ways. Which way is the most prone to cause mutation? A. Nonhomologous end- joining B. Excision repair C. Homologous recombination D. Mismatch repair

Answer 1

the non-homologous end-joining repairs the double-strand breaks, in the absence of a homologous sequence, if there is homologous sequence the double-strand break is repaired using homology-directed repair the, the homologous sequence is used as a template to synthesize the DNA at the double-strand break, so the homology-directed DNA repair is not error-prone.

Mismatch repair removes the incorrect nucleotide just after the replication, the nucleotide excision repair removes the modified nucleotides and adds the correct nucleotide.

the non-homologous end-joining repairs the double-strand breaks, in the absence of a homologous sequence, nucleotides at the ends of the DNA are removed and then Ku protein associates to the ends and then it recruits DNA PK catalytic subunits which then recruits Artemis and then activates it Artemis is a nuclease, it removes the single-stranded nucleotides at the ends of the DNA, then ligase IV ligates 2 ends of the DNA.

during non-homologous end-joining nucleotides are lost so this is an error prone mechanism to repair the double-strand breaks so the answer is

A. Nonhomologous end- joining