What Is PCR?

Polymerase Chain Reaction (PCR) is a technique used to amplify a specific piece of DNA, allowing researchers to create a large number of copies of a gene, bacterial strain, virus, or any other part of the genome. Originally developed in the late 1980s, PCR is one of the most powerful and commonly used tools in molecular biology. The ability to amplify a specific gene in a pool of unrelated DNA molecules revolutionized the study of genetics and opened up new possibilities in biotechnology, clinical diagnostics, forensics, and drug development.

How PCR Works

PCR is a physical process that begins with a sample of DNA, usually from a living organism such as a virus, bacterium, or human. The sample is divided into two parts and then mixed with a special mixture of primers, heat-stable enzymes, and other chemicals. The primers, which are short DNA sequences, are designed to recognize and bind to either end of the gene or other piece of DNA being studied.

When the sample is exposed to hot and cold cycles, molecules inside the sample form new bonds, allowing the primers to travel along the genetic material and initiate a reaction. The heat-stable enzymes inside the sample, called polymerases, then start making copies of the DNA using the nucleotides in the sample as “building blocks.” Each cycle of PCR doubles the amount of genetic material present in the sample.

Benefits of PCR

Since its initial development, PCR has been used in countless scientific studies and enabled researchers to make breakthroughs in many fields. PCR is relatively easy to perform, requires few resources and can be conducted effectively in many different laboratories. The technique has spawned a wide variety of related technologies and made it possible to sequence the genomes of many organisms, including humans. PCR is also used in clinical diagnostics to detect genetic and infectious diseases, such as HIV and hepatitis.

PCR’s many applications have made it one of the most important techniques in current biology and it continues to be important in research and clinical settings. With the discovery and development of new methods, PCR will likely remain an essential tool for studying the genetic code for many years to come.