A technique widely used in the biochemistry sciences.
First, Polymerase Chain Reaction (also known as PCR) is a technique that we use in the biochemistry sciences. Besides, PCR is a laboratory genetic technique. It applies in vitro to utilize amplification (the enzymatic synthesis of large quantities) of a chosen segment of the DNA. It also applies in a wide range of laboratory and clinical applications. Additionally, PCR synthesizes DNA and uses DNA polymerase (enzymes that cells use to replicate their DNA).
Second, we can use PCR to apply molecular techniques in the identification and characterization of some agents. For example, viral, bacterial, parasitic, and fungal. Besides, this technique is an essential tool in molecular biology. It allows the enzymatic synthesis of large quantities of nucleic acid sequences (DNA and RNA in repetitive cycles in vitro).
Polymerase Chain Reaction has revolutionized modern life science technology. It widely applies in researches and science applications.
Revolution of modern life science technology and K. B. Mullis.
Kary Banks Mullis was born on 28 December 1944 (Lenoir North, North Carolina, USA). In fact, he was the first man to invent the PCR. It took place in 1985 in a biotechnology company Cetus Corporation, located in Berkeley, California, USA. The company was the original owner of the PCR patent, which they sell to Hoffmann-La Roche Inc. in 1991.
Dr. Mullis obtained his bachelor’s degree in Chemistry from the Georgia Institute of Technology in 1966. In addition, he later received a Ph.D. in Biochemistry from the University of California at Berkeley in 1972. Mullis spent seven years doing post-doctoral research at the University of Kansas Medical School on Pediatric Cardiology and Pharmaceutical Chemistry. As well, in 1978, he got a technician position in Cetus Corporation of Emeryville, where he came up with an idea to create the PCR.
The idea to create the PCR
Then, in 1983, while Mullis was driving along the Pacific Coast Highway 128 of California, he thought about something. It was a simple method to determine a specific nucleotide from a long, stretched molecule of the DNA. From then, he claimed to have a sudden flash of an idea. He had conceived how to start and stop DNA polymerase action and repeating a way of amplifying a DNA sequence in a test tube. Later, Mullis took the idea to his colleagues at the Cetus Company. They immediately started to work out together an experimental system.
Meanwhile, they developed a technique, which they had presented to the rest of the world in 1985. The scientific community had widely accepted the idea. Therefore, in 1989, they named the enzyme molecule that uses PCR Taq Polymerase. During the same year, Cetus got the patent for the PCR technique. They later sold both patents, PCR and Taq Polymerase, to Hoffmann-La Roche for $300 million.
How do PCR works?
Of course, PCR amplifies the targeted DNA segment. Once it is over, we can use it in many different laboratory procedures. For example, mapping techniques in the Human Genome Project (HGP), DNA fingerprinting, detection of bacteria or viruses (especially AIDS), and in diagnosing genetic disorders.
Accordingly, we should first heat the sample by using a Peltier heat pump. The pump heats up and cools down the DNA and it separates two pieces of single-stranded DNA. Then, Taq polymerase (a bacterium that lives by volcanic sulfur jets at the bottom of the ocean where the temperature is very high) synthesizes or builds two new strands of DNA. In addition, the enzyme uses the original strands as templates. The process results in the duplication of the original DNA. Each of the new molecules contains one old and one new strand of DNA. Further, each of these strands creates two new copies and many more. The cycle of denaturing and synthesizing new DNA repeats as many as 30-40 times leading to more than a billion copies of the original DNA segment.
Finally, the cycling of the PCR is automated and can complete in a few hours. We can carry out the process using a thermo-cycler, programmed to alter the reaction temperature and allow DNA denaturing and synthesis.
Ehtisham, M., Wani, I., Wani, F., & Kaur, P. (2016). Polymerase Chain Reaction (PCR): Back to Basics. DOI Number: 10.5958/2320-5962.2016.00030.9
Ghannam MG, Varacallo M. Biochemistry, Polymerase Chain Reaction (PCR) [Updated 2018 Dec 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK535453/
Hongbao, M. (2005). Development Application of Polymerase Chain Reaction (PCR). The Journal of American Science, 3(1). http://www.jofamericanscience.org/journals/am-sci/0103/01-0198-%20mahongbao-am.pdf
National Human Genome Research Institute. 2015. Polymerase Chain Reaction (PCR) Fact Sheet. https://www.genome.gov/about-genomics/fact-sheets/Polymerase-Chain-Reaction-Fact-Sheet