PCR
PCR refers to a ‘polymerase chain reaction’, which is the process by which copies of DNA can be generated from a sample of the original DNA strand. A polymerase chain reaction allows for hundreds of copies of DNA to be made in a laboratory setting.
It works by heating the DNA sample to over 95 Celsius, which breaks the DNA hydrogen bonds which hold the DNA strand together. The polymerase enzyme makes replication possible, which is called ‘denaturing’ the DNA. Increasing heat breaks the DNA down, so that once temperature is then reduced, the strands reform and begin to pair up with themselves to form a new identical copy of the original targeted DNA. As the Polymerase reaction mixture creates many components of the essential parts of DNA, many more copies can be formed as part of the reaction cycle. For example, after the first run of the chain reaction cycle there will be two strands, then after the second reaction there will be four, and so on.
PCR allows for many copies of an original DNA strand to be made so that there are plenty of opportunities to analyse the original DNA data. The PCR method has also been used to advance cloning technology. PCR is also commonly used to determine or identify a person or an organism by examining or comparing DNA, and to establish links in DNA – for example from parent to child as is done in paternity testing. It is highly effective as only a small amount of original DNA data is needed to produce many samples ready for analysis.
