Question

In E. coli, the enzyme that fills gaps in duplexes by adding nucleotides to the 3’ end is called:

• A. Type II restriction endonucleases
• B. DNA polymerase I
• C. DNA ligase
• D. Terminal transferase

Hint:

DNA polymerase I = ”gap-filling enzyme” in prokaryotic DNA replication.

Answer 1

The Correct Option is B

E. coli DNA polymerase I fills DNA duplex gaps by adding nucleotides to the 3’ hydroxyl group. Its dual polymerase and exonuclease activities allow it to remove primers and synthesize replacement DNA.