Which DNA polymerase is mainly responsible for genome replication in E. coli?
The answer is (C), DNA Polymerase III. Polymerase I is mainly responsible for replacing the short segments of RNA primer at the start of each Okazaki fragment. Polymerase II primarily participates in replicating short segments during DNA repair, such as in the removal of thymine dimers. Topoisomerase is not directly involved in replication at all; it temporarily “nicks” the sugar-phosphate backbone of one strand, allowing the ends to rotate with respect to one another to prevent excessive supercoiling of the DNA.