- A Mainly the complete physical deletion of an entire target gene from the genome each time in standard practice under most conditions encountered
- B Precise conversion of one DNA base to another (e.g., C to T or A to G) without double-strand break, reducing off-target indels
- C Mainly large-scale chromosomal rearrangements, such as inversions and reciprocal translocations as frequently observed in practice
- D Editing that is restricted mainly to RNA transcripts, and rarely to genomic DNA itself directly in many documented cases
Correct answer: B. Precise conversion of one DNA base to another (e.g., C to T or A to G) without double-strand break, reducing off-target indels
Explanation: Base editors (Komor/Gaudelli): fuse catalytically dead Cas9 (or nickase) with base-modifying enzymes. CBEs: C to T conversion. ABEs: A to G conversion. No DSB needed, fewer indels.
Concept context
Recombinant DNA, GMOs, PCR, CRISPR, and biotechnology applications. Growing importance in NEET.
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