The RNA primer at the beginning of each Okazaki fragment is removed by
A)DNA polymerase I.
B)DNA polymerase II.
C)DNA polymerase III.
D)3' → 5' exonuclease subunit of DNA polymerase III.

Question

Quizplus · Accepted Answer

The RNA primer at the beginning of each Okazaki fragment is removed by DNA polymerase I. This enzyme has a 5' → 3' exonuclease activity that can remove RNA primers and replace them with DNA nucleotides. Once the RNA primer is removed, DNA polymerase I fills in the gap and DNA ligase seals the remaining nick in the backbone. DNA polymerase II and III are primarily involved in DNA replication and repair, but do not have the specific activity needed to remove RNA primers. The 3' → 5' exonuclease activity of DNA polymerase III is involved in proofreading the newly synthesized DNA strand during replication.

The RNA Primer at the Beginning of Each Okazaki Fragment