Question

Regarding DNA polymerase I, which one of the following is correct?

• A. Not required in bacteria
• B. Repairs any damage within DNA
• C. Involved in Okazaki fragment processing
• D. Participates in DNA replication

Hint:

This polymerase is the repair and primer-removal enzyme, not the main replicase.

Answer 1

The Correct Option is B

Step 1: DNA polymerase I is a prokaryotic enzyme with polymerase, 5'-to-3' exonuclease and 3'-to-5' proofreading exonuclease activities. Its main role is in DNA repair.

Step 2: Its principal function is to repair damage within DNA. It also removes RNA primers and fills the gaps between Okazaki fragments, after which DNA ligase seals the nicks. So the correct statement is that it repairs damage within DNA.

Step 3: The actual processive enzyme of bacterial replication is DNA polymerase III, not Pol I, so calling Pol I the main replication enzyme is misleading. Pol I is certainly required in bacteria, so the option "not required in bacteria" is false.

Step 4: Among the choices given, the single most accurate statement about Pol I is that its principal job is repair, hence that option is selected.