The Polymerase Chain Reaction

The polymerase chain reaction (PCR) is a process for building very small amounts of DNA so that they can be viewed and evaluated or used in other scientific methods. PCR is widely used in almost all branches of biology, including molecular biology, microbiology, genetics, environmental sciences, food science, biotechnology, forensics and clinical diagnostics. The PCR technique involves using a DNA polymerase enzyme to improve (duplicated several times) a piece of DNA. The original molecule of DNA is copied by the enzyme DNA polymerase, effectively doubling the number of DNA molecules.

Then each of these molecules is duplicated in a second replication cycle, resulting in four molecules. Again, each of these molecules are duplicated by the third enzyme replication cycle. The process is called a chain - hence the name. "Polymerase chain reaction" The original piece of DNA is amplified over many cycles, generating millions of copies of the original DNA molecule often the PCR experiment is simply out of presence. or absence of a specific type of DNA to check, but sometimes also used the PCR to provide sufficient DNA for use in a subsequent experiment to generate a clone or DNA sequencing. The original PCR process was adapted to an expanding range of genetic, diagnostic tests, and many other applications to run.

Modern variants of PCR include real-time PCR. This technology allows the newly generated DNA molecules to be tested immediately they are produced. This ability to process real-time PCR, while the reaction still occurs, is of great use to scientists because it reduces the amount of time required for a result (particularly important in the clinical diagnosis) and allows generation also the quantification of DNA. Real-time PCR can not only answer the question "what is this DNA?" but "how much DNA is present?".