Answer:
DNA primers
Step-by-step explanation:
PCR uses short DNA segments called as primers. These primers become paired with the template DNA strands and are being elongated by the DNA polymerase enzyme (Taq polymerase). On the other hand, in vivo DNA replication does not use the DNA primers. Primase is the enzyme that makes RNA primers with free 3' OH end which is then elongated by DNA polymerases. The RNA primers are synthesized when the primase enzyme makes a short RNA copy of the DNA template strand.