Question

How does PCR differ from DNA replication?

Answer 1

Hint: PCR stands for Polymerase Chain Reaction and is an in-vitro process of amplification of DNA while Replication is in-vivo amplification of DNA.

Complete answer:
PCR (polymerase chain reaction) is a technique in molecular biology which is used for the amplification of a specific fragment of DNA. The main purpose of this reaction is to make exponential copies of the single DNA fragment. In contrast, DNA replication is the natural in-vivo process to copy the whole genome at once before cell division.

The PCR requires a high temperature (80-90 degree C) for the denaturation purpose, therefore, the polymerase used in this is thermostable polymerase i.e. TaqPolymerase which is derived from archaebacteria while the replication occurs at the normal body temperature (37 degree Celsius) so there are many polymerases present in the body.

DNA replication is a process with high speed, fidelity, and accuracy while the TaqPolymerase used in PCR has no proofreading activity. The PCR requires two types of primers of the reaction i.e. forward and backward primers while the DNA replication uses RNA primers synthesized by primase.

The DNA replication requires helicase, primase, and topoisomerase for replication fork formation while no replication fork is formed in PCR. Also, PCR requires dNTPs and artificial primers.

PCR is necessary to obtain many copies of a specific fragment of DNA for the experimental process and it is a discontinuous process i.e. it will run for 30-40 cycles only while Replication of DNA is a necessary event for every organism before division and it is a continuous process.

Note: TaqPolymerase operates at 72 degree C while DNA polymerase operates at 37 degree C (human body temperature). It is a thermostable DNA Polymerase which is obtained from a bacteria called Thermus aquaticus. It is abbreviated as Taq or Taq pol.