Question

DNA polymerase III adds nucleotides ________.

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 1

DNA polymerase III adds 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 primers are later replaced by DNA nucleotides.

Step-by-step explanation:

DNA polymerase III adds nucleotides to the 3' end of the RNA primer. The RNA primer provides a free 3'-OH group that is essential for the addition of nucleotides, as DNA polymerase III can only add nucleotides in a 5' to 3' direction and requires a pre-existing 3'-OH group to which it can attach new nucleotides. During the process of DNA replication, DNA polymerase III continuously adds nucleotides to the leading strand and to the Okazaki fragments on the lagging strand, each time starting from an RNA primer synthesized by RNA primase. After the RNA primer is removed, the nucleotides previously occupied by the RNA are replaced with DNA nucleotides.