Xeroderma pigmentation is caused due to a group of closely related abnormalities in -

Ans. is 'c' i.e., Nucleotide excision repairo This question is repeat from AIIMS-2005Nucleotide excision repairo UV rays cause DNA damage by forming TT dimmers which prevent replication,o Enzyme UV specific endonclease (UVr ABC excinuclease) cleaves the damaged strand on both sides,o DNA polymerase fills the gap & DNA ligase seals the nick. Example of disease associated with defective nucleotide excision repair is xeroderma pigmentosum. Due to defecdve nucleotide excision repair, there is formation of bulky DNA lesions as a result of formation of thymidine dimers caused by UV rays induced damage.