In Escherichia coli, which enzymatic activity is responsible for removing the short RNA primers from Okazaki fragments?

• A 3' to 5' exonuclease activity of DNA polymerase III
• B Helicase activity of DnaB
• C Endonuclease activity of DNA gyrase
• D 5' to 3' exonuclease activity of DNA polymerase I ✓

Explanation

DNA polymerase I uniquely carries a 5' to 3' exonuclease activity that excises RNA primers while simultaneously filling the gap, a process called nick translation. The 3' to 5' exonuclease of both polymerases serves only proofreading of newly inserted bases and cannot remove primers lying ahead of the growing point. DnaB helicase unwinds parental duplex DNA and does not degrade RNA.

Reference: Lehninger Principles of Biochemistry, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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