Which enzyme joins Okazaki fragments on the lagging strand during DNA replication by catalyzing phosphodiester bond formation?
Answer and explanation
Correct answer: A. DNA Ligase
- Step 1: Discontinuous synthesis on the lagging strand produces discrete Okazaki segments with nicks in the phosphate backbone. Step 2. DNA ligase uses ATP (or NAD+) to form covalent phosphodiester bonds sealing the adjacent fragments together. Answer: DNA Ligase. Why not the others: DNA helicase separates parental strands; DNA polymerase I removes primers; SSBs prevent premature reannealing.
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