<P> A primer is a short strand of RNA or DNA (generally about 18 - 22 bases) that serves as a starting point for DNA synthesis . It is required for DNA replication because the enzymes that catalyze this process, DNA polymerases, can only add new nucleotides to an existing strand of DNA . The polymerase starts replication at the 3' - end of the primer, and copies the opposite strand . </P> <P> In vivo DNA replication utilizes short strands of RNA called RNA primers to initiate DNA synthesis on both the leading and lagging strands--DNA primers are not seen in vivo in humans . These RNA primers can be made de novo . </P>

Why we use rna primer in dna replication
find me the text answering this question