Polymerase Chain Reaction is abbreviated as PCR. PCR is the fastest cloning technique. When the DNA vector is isolated and introduced into the host cell, the desired gene is spliced with the host and numerous copies are made. In 1984, American scientist Kary Mullis invented the PCR technique.
Step-1: First the desired piece of DNA is heated to 95 degrees C. It separates the DNA strands. As a result, the primers bind to the designated sites. This step is called Denaturing step.
Step-2: Very quickly the temperature of the process is brought down. Primers bind to DNA primers. However, the actual temperature may be lower or higher depending on the length and sequence of the primer. A reaction that occurs once is called a cycle.
Step-3: At this stage, the reaction temperature is 45 degrees Celsius. is kept at (dNTPs) In the presence of Mg2+ ions, nucleotides link together to form new complementary DNA strands.
Step-4: The resulting DNA molecules are separated again by heat. Primer-1 binds to the 5→3 primer and Primer-2 binds to the 3→5 primer. At the end of the second cycle, the two progenitors make two new DNAs. The number of DNA molecules in each cycle will double that of the previous cycle.
With a machine, the reactions that make DNA go one after the other. This device is called thermal cycler. Each step takes 2-5 minutes. The reaction is limited to 25-35 cycles. One molecule of DNA will produce 235(2n) = 3.5×1010 molecules of DNA after 35 cycles.