DNA Structure and Replication · USMLE Step 1

During DNA replication, which enzyme replaces RNA primers on the lagging strand with DNA in prokaryotes?

  1. DNA polymerase III
  2. DNA polymerase I
  3. DNA ligase
  4. RNA primase
Show answer and explanation

Correct answer: DNA polymerase I

In prokaryotes, DNA polymerase I has exonuclease activity to remove RNA primer segments and fills in the corresponding gaps with DNA prior to ligation.

Difficulty: Medium Question 16 of 20

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