Final answer:
During DNA replication, an RNA primer is added to the DNA template to provide the starting point for nucleotide addition by supplying the necessary 3' OH end that DNA polymerase requires.
Step-by-step explanation:
During DNA replication, a primer added to a DNA template serves as the beginning site of nucleotide addition. The primer provides the necessary 3' OH end of the sugar group that DNA polymerase III requires in order to start DNA synthesis. This primer is an RNA sequence that is synthesized by RNA primase. The RNA primer is complementary to the parental or template DNA and provides a free 3'-OH group where DNA nucleotides can be added.
To facilitate DNA replication, an enzyme called helicase unwinds the DNA at the origin of replication, creating a site for the RNA primer to bind and initiating the replication process. As the primer provides the starting free 3'-OH group, DNA polymerase III can extend the DNA strand by adding nucleotides one by one, complementary to the template strand.