Question

during dna replication in e. coli, which of the following enzymes removes the rna nucleotides from the primer and adds equivalent dna nucleotides to the 3 end of okazaki fragments?

helicase

dna polymerase iii

ligase

dna polymerase i

Explanation:

To solve this, we analyze each enzyme's function in DNA replication in E. coli:

• Helicase: Unwinds the DNA double helix, not involved in primer removal or DNA addition.
• DNA polymerase III: Synthesizes new DNA strands (leading and lagging) but doesn't remove RNA primers.
• Ligase: Joins Okazaki fragments together, not involved in primer removal or DNA addition to Okazaki fragments' 3’ ends.
• DNA polymerase I: Has 5’→3’ exonuclease activity to remove RNA primers and 5’→3’ polymerase activity to add DNA nucleotides to the 3’ end of Okazaki fragments.

Answer:

D. DNA polymerase I