Answer:
Primers are short sequences that allow the initiation of DNA synthesis.
Explanation:
DNA polymerases are the enzymes of chain elongation and cannot start the synthesis of new DNA strands. These enzymes can only add new deoxyribonucleotides to the existing DNA or RNA strands in 5' to 3' direction.
Primase enzymes form short stretches of RNA using DNA template strands. These short RNA fragments are called RNA primers. DNA polymerases serve to elongate the primers by adding new deoxyribonucleotides to the 3' end of the primer.
The 3' OH group present at the 3' end of the primer serves as a nucleophile and a phosphodiester bond is formed between 3' end of the primer and the alpha phosphorus of incoming deoxyribonucleotide.