polymerase chain reaction

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polymerase chain reaction

(pŏl`ĭmərās') (PCR), laboratory process in which a particular DNA segment from a mixture of DNA chains is rapidly replicated, producing a large, readily analyzed sample of a piece of DNA; the process is sometimes called DNA amplification.

The Process

In PCR, DNA (see nucleic acidnucleic acid,
any of a group of organic substances found in the chromosomes of living cells and viruses that play a central role in the storage and replication of hereditary information and in the expression of this information through protein synthesis.
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) is immersed in a solution containing the enzymeenzyme,
biological catalyst. The term enzyme comes from zymosis, the Greek word for fermentation, a process accomplished by yeast cells and long known to the brewing industry, which occupied the attention of many 19th-century chemists.
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 DNA polymerase, unattached nucleotide bases (the subunits that DNA is composed of), and "primers," short sequences of nucleotides designed to bind with an end of the desired DNA segment. Two primers are used: one primer binds at one end of the desired segment on one of the two paired DNA strands, and the other primer binds at the other end but on the other strand. The solution is heated to break the bonds between the strands of the DNA. When the solution cools, the primers bind to the separated strands, and DNA polymerase quickly builds a new strand by joining the free nucleotide bases to the primers. When this process is repeated, a strand that was formed with one primer binds to the other primer, resulting in a new strand that is restricted solely to the desired segment. Thus the region of DNA between the primers is selectively replicated. Further repetitions of the process can produce billions of copies of a small piece of DNA in several hours.

Development and Applications

PCR was developed in 1985 by Kary B. Mullis, who was awarded the 1993 Nobel Prize in chemistry for his work. It is used in DNA fingerprintingDNA fingerprinting
or DNA profiling,
any of several similar techniques for analyzing and comparing DNA from separate sources, used especially in law enforcement to identify suspects from hair, blood, semen, or other biological materials found at the scene of a violent
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 and in medical tests to identify diseases from the infectious agent's DNA. In forensic use, the test can be used to compare two samples of DNA, usually by looking at matches (or mismatches) of six inherited traits (e.g., hair curliness) from each of the samples. Each trait is controlled by a single gene, each gene having at least two forms, or alleles, resulting in 21 combinations of these alleles, some of them very rare. A nonmatch conclusively excludes a suspect. PCR also is used in taxonomic classificationclassification,
in biology, the systematic categorization of organisms into a coherent scheme. The original purpose of biological classification, or systematics, was to organize the vast number of known plants and animals into categories that could be named, remembered, and
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 to help show evolutionary relationships between organisms on the molecular level. It has the advantage of being able to be used even when only very small samples, such as tiny pieces of preserved tissue from extinct animals, are available.

polymerase chain reaction

[pə¦lim·ə‚rās ′chān rē‚ak·shən]
(cell and molecular biology)
A technique for copying and amplifying the complementary strands of a target deoxyribonucleic acid molecule. Abbreviated PCR.
References in periodicals archive ?
A polymerase chain reaction-based technique was applied for the diagnosis of malaria and detection of responsible species in the patients who were suspected to carry the parasite.
ABBREVIATIONS: bDNA = Branched DNA; DNA = Deoxyribonucleic Acid; dNTP = Deoxyribonucleotides; dATP = Deoxyadenosine Triphosphate; dCTP = Deoxycytidine Triphosphate; dGTP = Deoxyguanosine Triphosphate; dTTP = Deoxythymidine Triphosphate; FDA = Food and Drug Administration; FRET = Fluorescence Resonance Energy Transfer; MRSA = Methicillin Resistant Staph aureus; MTB = Mycobacterium tuberculosis; NASBA = Nucleic Acid Sequence Based Amplification; PCR = Polymerase Chain Reaction; PFGE = Pulsed-Field Gel Electrophoresis; RT-PCR = Reverse Transcription Polymerase Chain Reaction; Taq = Thermus aquaticus; TMA = Transcription-Mediated Amplification; VRE = Vancomycin Resistant Enterococcus.
Identification of Thunnus tuna species by the polymerase chain reaction and direct sequence analysis of their mitochondrial cytochrome-b gene.
The polymerase chain reaction, or PCR, found its way into many areas in biology very soon after its invention by the American Kary Mullis in 1983, who received a Nobel Prize for his discoveries in 1993.
Nested polymerase chain reaction (PCR) VZV DNA results were negative both in the personal air samples and in saliva.
SAN FRANCISCO -- The dried blood spot polymerase chain reaction test is a sensitive, specific, and cost-effective way to carry out large-scale screening of newborns for congenital cytomegalovirus infection, Dr.
Techniques mastered during the program include agarose, polyacrylamide and protein gel electrophoresis, DNA sequencing, gene mapping, restriction enzyme cleavage of DNA, recombinant gene technology, cloning, polymerase chain reaction (PCR), reverse transcription polymerase chain reaction (rtPCR), Southern and Western blotting, analysis of restriction fragment polymorhisms (RFLP), analysis of variable number tandem repeats (VNTR's), DNA fingerprinting for paternity and forensics analysis, protein analysis and bioprocessing.
Their histologic features are similar to those of papillomatous lesions in the airway, and polymerase chain reaction may identify human papillomavirus (HPV) DNA in the specimen.
Real-time polymerase chain reaction (RT-PCR) and flow cytometry were used to quantify elevated cytokine production as an indicator of inflammatory responses to four commercial dental resins.
In order to examine the role of MOG in the CNS, the human MOG gene was spliced using reverse transcriptase polymerase chain reaction (RT-PCR).
Companies that manufacture such allograft material therefore should improve the level of serology screening to include polymerase chain reaction detection of DNA viruses, recommended Dr.
1983 To speed up the process of reproducing tiny bits of DNA, biochemist Kary Mullis develops a technique called polymerase chain reaction.

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