Which enzyme initiates base excision repair by removing a damaged base, creating an abasic site?

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Multiple Choice

Which enzyme initiates base excision repair by removing a damaged base, creating an abasic site?

Explanation:
In base excision repair, the initiating step is the removal of a damaged base by a DNA glycosylase. This enzyme recognizes the specific lesion and cleaves the N-glycosidic bond between the damaged base and the sugar backbone, producing an abasic (AP) site. That abasic site then becomes the target for the next steps: AP endonuclease cuts the backbone at the AP site, DNA polymerase fills in the correct nucleotide, and ligase seals the strand. The other enzymes don’t start the process by removing the base—they act after the base has already been removed or perform different tasks.

In base excision repair, the initiating step is the removal of a damaged base by a DNA glycosylase. This enzyme recognizes the specific lesion and cleaves the N-glycosidic bond between the damaged base and the sugar backbone, producing an abasic (AP) site. That abasic site then becomes the target for the next steps: AP endonuclease cuts the backbone at the AP site, DNA polymerase fills in the correct nucleotide, and ligase seals the strand. The other enzymes don’t start the process by removing the base—they act after the base has already been removed or perform different tasks.

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