Which enzyme is responsible for removing RNA primers and replacing them with DNA in prokaryotes?

Which enzyme is responsible for removing RNA primers and replacing them with DNA in prokaryotes?

• A. DNA ligase
• B. DNA polymerase I
• C. DNA helicase
• D. Primase

Answer: (B)

In prokaryotic DNA replication, removing RNA primers and replacing them with DNA is carried out by DNA polymerase I. It has a 5' to 3' exonuclease activity that chews away the RNA primers and a 5' to 3' polymerase activity that fills in the resulting gaps with DNA. After this primer-removal and gap-filling step, DNA ligase seals the remaining nick to join the DNA fragments. Other enzymes have different roles: helicase unwinds the double helix, primase synthesizes the RNA primers, and DNA polymerase III is the main enzyme that extends DNA during replication but lacks the dedicated exonuclease activity needed to remove RNA primers.

In prokaryotic DNA replication, removing RNA primers and replacing them with DNA is carried out by DNA polymerase I. It has a 5' to 3' exonuclease activity that chews away the RNA primers and a 5' to 3' polymerase activity that fills in the resulting gaps with DNA. After this primer-removal and gap-filling step, DNA ligase seals the remaining nick to join the DNA fragments.

Other enzymes have different roles: helicase unwinds the double helix, primase synthesizes the RNA primers, and DNA polymerase III is the main enzyme that extends DNA during replication but lacks the dedicated exonuclease activity needed to remove RNA primers.