DNA Polymerase III in DNA Replication Process

What is the role of DNA polymerase III in DNA replication?

A. to the 3' end of the RNA primer

B. in the place of the primer RNA after it is removed

C. to the 5' end of the RNA primer

D. to internal sites in the DNA template

E. to both ends of the RNA primer

Answer:

DNA polymerase III adds nucleotides to the 3' end of the RNA primer.

DNA polymerase III plays a crucial role in the DNA replication process. It is responsible for adding nucleotides to the 3' end of the RNA primer, which is synthesized by RNA primase to provide a starting point for DNA synthesis.

The RNA primer, with its free 3'-OH group, is essential for DNA polymerase III to add nucleotides in a 5' to 3' direction. This enzyme requires a pre-existing 3'-OH group to attach new nucleotides during replication.

During DNA replication, DNA polymerase III continuously adds nucleotides to the leading strand and to the Okazaki fragments on the lagging strand. Each time, it begins synthesis from an RNA primer produced by RNA primase.

After DNA synthesis is complete, the RNA primers are removed, and the spaces previously occupied by RNA are filled with DNA nucleotides. This ensures the formation of a complete and accurate DNA molecule.