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Understanding What the Polymerase Chain Reaction (PCR) Test Is All About
Polymerase chain reaction (PCR) is a method for amplifying very small DNA amounts located on any material, solid or liquid. It is important to appreciate the fact that every living being contains sequences of DNA that are unique to not only their species but to the individual member of the species. Scientists studying the DNA sequence can do so even more easily even if the DNA sample is very scanty because by employing the PCR technique it permits the making of countless identical copies of the sequence so that they can determine with more certainty the identity of the DNA source.
The Process of DNA Matching
The process of identification may start with PCR amplification if the original material containing the DNA sequence is not enough to permit proper testing. Once the desired DNA sequence has been amplified by the PCR process, the amplified segments then have to be compared and matched against the DNA sequence of a known source that could be human, animals or pathogen, so that it can be established whether there is a match or not. To make the comparison, the DNA sequence from a known source is placed next to the PCR-generated nucleotide sequences in a separating gel through which an electrical current is passed. The different nucleotide sequences make up bands that look like a ladder according to the size of their molecules and electrical charge. The identity of the DNA sequences is revealed by the bands that migrate to the same levels in both the samples. In the labs, the entire process is done using PCR test kits; MyBioSource PCR kits are among the most popular due to their high quality and easy availability.
The process of PCR
The PCR can be done in a test tube equipped with a special heater and some chemicals. You need the sample containing the nucleotide sequence, DNA primers, DNA polymerase containing Adenine, Thymidine, Cytosine, and Guanine nucleotides that form the complementary DNA nucleotide strands in a particular sequence. The DNA sample is placed along with the reagents in a test tube and heated to 940 C to break the hydrogen bonds allowing the formation of complementary DNA bonds. When the mixture cools to 540 C the DNA anneals to make new DNA molecules with double strands from each of the individual strands of the original molecule. With the cycle being repeated 40 times in a thermal cycler, the original single DNA sequence multiplies to 100 billion copies because of the doubling achieved in each cycle.
The PCR test helps physicians to diagnose and treat patients with several tests, including the identification of pathogenic organisms that may be difficult to cultivate. PCR may also be ordered for diagnosing genetic diseases, and identification of genetic rearrangements and mutations in certain cancers. The PCR technique has also been used successfully to identify biological relationships, especially when the identity of a child’s parent is in doubt. However, one of the most high-profile applications of PCR technology that has caught the imagination of the public is in areas of genetic fingerprinting, evolutionary biology, as well as the forensic investigation that helps to apprehend criminals or to prove the accused innocent of grave crimes.