During prokaryotic DNA replication, RNA primers laid down by primase must be removed and replaced with DNA. Which activity of DNA polymerase I is responsible for removing the RNA primer?

• A 5'→3' polymerase activity
• B 5'→3' exonuclease activity ✓
• C 3'→5' exonuclease activity
• D Helicase activity

Explanation

DNA polymerase I removes RNA primers via its 5'→3' exonuclease activity while simultaneously replacing them with DNA through its 5'→3' polymerase activity, a process called nick translation. The 3'→5' exonuclease activity serves proofreading of newly synthesized DNA. DNA polymerase III is the main replicative polymerase in prokaryotes but lacks the ability to remove primers, making DNA Pol I essential for Okazaki fragment maturation.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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