The primary enzyme responsible for direct reversal of UV-induced TT dimers are
Show Hint
- glycosylases
- photolyases
- exonucleases
- endonucleases
The Correct Option is B
Solution and Explanation
Step 1: Concept
Direct reversal is a DNA repair mechanism that fixes damage without removing nucleotides, specifically targeting common lesions like thymine dimers.
Step 2: Meaning
TT dimers (cyclobutane pyrimidine dimers) occur when adjacent thymine bases on a DNA strand become covalently linked due to UV radiation.
Step 3: Analysis
Photolyases are specialized enzymes that use visible light energy to break the covalent bonds of the pyrimidine dimers, restoring the original bases. Glycosylases, exonucleases, and endonucleases are involved in excision repair pathways, which involve cutting the DNA backbone.
Step 4: Conclusion
Since the question asks for the enzyme responsible for "direct reversal" of these specific dimers, photolyase is the correct answer. Final Answer: (B)
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