Question:
Adenine can undergo a spontaneous change to hypoxanthine in a cell, leading to a DNA base pair mismatch. The CORRECT combination of enzymes involved in repairing this damage is:
Adenine can undergo a spontaneous change to hypoxanthine in a cell, leading to a DNA base pair mismatch. The CORRECT combination of enzymes involved in repairing this damage is:
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Base excision repair always follows the sequence: remove base → fill gap → seal strand.
Updated On: Nov 27, 2025
- Nuclease, DNA polymerase, DNA ligase
- Nuclease, DNA ligase, helicase
- Primase, DNA polymerase, DNA ligase
- Primase, helicase, DNA polymerase
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The Correct Option is A
Solution and Explanation
Spontaneous deamination of adenine produces hypoxanthine, which mispairs with cytosine. This type of damage is corrected by the base excision repair (BER) pathway.
In BER:
1. A nuclease (glycosylase + AP endonuclease) removes the damaged base and cuts the backbone.
2. DNA polymerase fills the correct nucleotide.
3. DNA ligase seals the final nick.
Thus, the correct combination is (A).
In BER:
1. A nuclease (glycosylase + AP endonuclease) removes the damaged base and cuts the backbone.
2. DNA polymerase fills the correct nucleotide.
3. DNA ligase seals the final nick.
Thus, the correct combination is (A).
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