After reading this article, don't say you don't know PCR technology

After reading this article, don't say you don't know PCR technology

After reading this article, don't say you don't know PCR technology

I. What is PCR

PCR, short for Polymerase Chain Reaction, is a method for amplifying a few or tens of copies of DNA to millions of copies, and it is one of the most important technologies to date. PCR has been widely used in paternity testing and criminal investigations.

PCR can be thought of as a technique similar to the process of DNA replication that occurs in cells, which results in the production of new complementary DNA fragments using the original DNA as a template. The replication of DNA in cells is a very complex process. A variety of factors are involved in replication. PCR is a DNA replication reaction performed in a test tube and the basic principle is similar to intracellular DNA replication, but the reaction system is relatively simple.

II. Basic principle of PCR

The basic principle of PCR is to take the DNA to be amplified as the template, use a pair of oligonucleotide fragments complementary to the 5′ and 3′ ends of the template as the primers, under the action of DNA polymerase extend along the template strand according to the mechanism of semi-conserved replication until the completion of new DNA synthesis, and repeat this process to make the target DNA fragment amplified.

III. Basic steps of PCR

① Denaturation: Heat the reaction system to 95°C to denature all the template DNA into single-stranded DNA.

② Annealing: Decrease the temperature to the appropriate temperature to anneal the primers to the template DNA.

③ Extension: Increase the temperature to 72°C and DNA polymerase catalyzes the synthesis reaction of DNA with dNTP substrate.

The above three steps are called a cycle, and such a cycle is repeated 25-30 times to obtain a large amount of target DNA.