Which of the Following Types of DNA Damage Cannot Be

Question

Which of the following types of DNA damage cannot be repaired by base excision repair?
A) Depurination
B) Cytosine deamination
C) Thymine dimer
D) Single-strand break
E) Base oxidation

Accepted Answer

Base excision repair involves the removal of damaged bases by specific enzymes (DNA glycosylases) and subsequent repair of the resulting abasic site. Thymine dimer, which occurs when two adjacent thymine bases become covalently bonded, is not recognized by DNA glycosylases and therefore cannot be repaired by base excision repair. Instead, it is repaired by the nucleotide excision repair pathway.