Correct option is A
Explanation-
Direct Repair:
This method directly reverses the damage to the DNA without removing the base or nucleotide. There is no base or nucleotide excision involved.
Example: Photolyase enzyme reversing UV-induced thymine dimers or alkyltransferase removing alkyl groups from O6-methylguanine.
Base Excision Repair (BER):
The damaged base is excised by a DNA glycosylase, creating an abasic site. Then, an AP endonuclease cuts the DNA backbone. A DNA polymerase fills the gap, and DNA ligase seals it. It involves removal and replacement of the damaged portion.
Incorrect Options-
Option b : Mentions homologous recombination, which is unrelated to both direct repair and BER.
Option c: Talks about non-homologous end joining (again, unrelated to these repair types).
Option d : Mentions a translesion polymerase in BER, which is associated more with translesion synthesis, not base excision repair.
So, Option a clearly and accurately distinguishes between direct repair and base excision repair.
