 Polymerase chain reaction. Polymerase chain reaction is a technique which is also called as technique of molecular biology. It is extensively used in the experiments of molecular biology as well as in biotechnology. Its name, the polymerase chain reaction is from one of its components. The name of that component is DNA polymerase. So the name derived polymerase chain reaction was actually from the DNA polymerase. As the PCR mean polymerase chain reaction progresses, the DNA which is amplified as a result of few initial cycles of the PCR that DNA is used as a template. So PCR is actually a replication or application process in which DNA is replicated. Initially template is provided, but later on the amplified product is used as a DNA or used as a template for the next coming cycles of the polymerase chain reaction. So in this way the DNA produced during the first cycles is used for the next coming cycles of the PCR. This sets of a motion of cycles means from DNA which was produced from the initial cycles that DNA will be used in the later on. So it starts or it works like a chain. That is the reason it is called as polymerase because the DNA polymerase amplifies the DNA and it works in the form of a chain reaction. So it is called as DNA polymerase chain reaction. During PCR means during polymerase chain reaction a heat stable DNA polymerase is used. This DNA polymerase was initially identified or it was purified from a bacterium which is found in hot springs. The name of dead bacterium is the bacterium thermosequaticus. So the first time the DNA polymerase was purified from thermosequaticus that is a bacterium and dead DNA polymerase was used for the PCR. So if we conclude that what is PCR? PCR is actually a molecular biology technique which is used to amplify the DNA and its derivatives or its modified forms can be used in different experiments of recombinant DNA technology, molecular genetics, molecular biology and in many states that can be studies that is related to the viruses or bacteria.