Question

Which DNA polymerase is responsible for the removal of the RNA primers at the origin and at the 5' ends of the Okazaki fragments in E. coli?

Options:
A. DNA Ligase
B. DNA Polymerase I
C. DNA Polymerase II
D. DNA Polymerase III

Answer 1

DNA Polymerase I is responsible for removing RNA primers from Okazaki fragments and the origin in E. coli, replacing them with DNA nucleotides, which DNA ligase then seals into a continuous strand. The correct option is A.

Step-by-step explanation:

The enzyme responsible for the removal of the RNA primers at the origin and at the 5' ends of the Okazaki fragments in E. coli is DNA Polymerase I. This enzyme not only removes the RNA primers through its 5'→3' exonuclease activity, but it also fills in the gaps with the appropriate deoxynucleotides.

After DNA Polymerase I adds the DNA nucleotides, DNA ligase is responsible for sealing the fragments, creating a continuous DNA strand on the lagging strand.

It is important to note that DNA Polymerase I has a unique role in DNA repair due to its enzymatic abilities, including this exonuclease activity which is not found in DNA Polymerase II or III. Option A. is the correct one.