“polymerase chain reaction”的概念、定义、翻译、参考文献-科学参考

polymerase chain reaction

Chemistry

A technique used to produce a very large number of copies of fragments of DNA. It was invented by Kary Mullis (1944– ) in 1983. The first part of the technique, known as DNA melting, consists of heating the DNA with the required segment to unravel the DNA double helix. The target sequence of DNA is then marked out with primers, i.e. short DNA fragments complementary to the target region. If DNA polymerase is then added together with the appropriate nucleotides, then two copies of the target sequence are produced. These copies can be reproduced in the same way, starting by heating. Repeating this process many times results in the production of a very large number of copies in several hours. PCR has many important medical applications.

Biology

A technique used to replicate a fragment of DNA so as to produce many copies of a particular DNA sequence. PCR can be employed as an alternative to gene cloning as a means of amplifying genetic material for DNA sequencing, and to provide the DNA fragments for cloning. The technique has also proved invaluable in forensic science, enabling amplification of minute traces of genetic material for DNA profiling or for detecting microsatellite DNA, and is used for a host of other applications, including DNA fingerprinting and DNA barcoding. The two strands of the DNA are separated by heating and short sequences of a single DNA strand (primers) are added, together with a supply of free nucleotides and a heat-stable DNA polymerase (e.g. Taq polymerase obtained from Thermus aquaticus, a hadobacterium that can withstand extreme heat, or Pfu polymerase from the archaean Pyrococcus furiosus). DNA polymerase uses single-stranded DNA as its template but requires a short section of double-stranded DNA to initiate the replication reaction. Hence, synthetic oligonucleotide primers are constructed so that their sequences are complementary to short regions flanking the 3′ region of DNA that is to be amplified; the oligonucleotides hybridize with the flanking sequences, forming the necessary double-stranded primers. In a series of heating and cooling cycles, the DNA sequence flanked by the primers doubles with each cycle and is thus rapidly amplified. Reverse transcription PCR (RT-PCR) is used for amplifying molecules of RNA, by initially converting the RNA into its complementary DNA molecule using the enzyme reverse transcriptase and then following the standard procedure for PCR. It can be used to analyse gene expression in samples taken from certain tissues or under particular conditions. Real-time PCR (RT-PCR) or quantitative PCR (qPCR) is a variant of the technique used for quantitatively estimating amounts of RNA or DNA in a sample. Essentially, it measures the rate of accumulation of DNA through successive cycles of PCR, on the basis that the more target molecules present in the starting sample, the faster is their subsequent amplification. All newly synthesized copies of the target are tagged with a fluorescent marker, and continuous monitoring of the amount of fluorescence indicates the rate of amplification and hence the amount of target molecule in the original sample. See also directed evolution; randomly amplified polymorphic DNA.
https://www.dnalc.org/resources/animations/pcr.html Animated account of PCR from the DNA Learning Center

单词	polymerase chain reaction
释义	polymerase chain reaction Chemistry A technique used to produce a very large number of copies of fragments of DNA. It was invented by Kary Mullis (1944– ) in 1983. The first part of the technique, known as DNA melting, consists of heating the DNA with the required segment to unravel the DNA double helix. The target sequence of DNA is then marked out with primers, i.e. short DNA fragments complementary to the target region. If DNA polymerase is then added together with the appropriate nucleotides, then two copies of the target sequence are produced. These copies can be reproduced in the same way, starting by heating. Repeating this process many times results in the production of a very large number of copies in several hours. PCR has many important medical applications. Biology A technique used to replicate a fragment of DNA so as to produce many copies of a particular DNA sequence. PCR can be employed as an alternative to gene cloning as a means of amplifying genetic material for DNA sequencing, and to provide the DNA fragments for cloning. The technique has also proved invaluable in forensic science, enabling amplification of minute traces of genetic material for DNA profiling or for detecting microsatellite DNA, and is used for a host of other applications, including DNA fingerprinting and DNA barcoding. The two strands of the DNA are separated by heating and short sequences of a single DNA strand (primers) are added, together with a supply of free nucleotides and a heat-stable DNA polymerase (e.g. Taq polymerase obtained from Thermus aquaticus, a hadobacterium that can withstand extreme heat, or Pfu polymerase from the archaean Pyrococcus furiosus). DNA polymerase uses single-stranded DNA as its template but requires a short section of double-stranded DNA to initiate the replication reaction. Hence, synthetic oligonucleotide primers are constructed so that their sequences are complementary to short regions flanking the 3′ region of DNA that is to be amplified; the oligonucleotides hybridize with the flanking sequences, forming the necessary double-stranded primers. In a series of heating and cooling cycles, the DNA sequence flanked by the primers doubles with each cycle and is thus rapidly amplified. Reverse transcription PCR (RT-PCR) is used for amplifying molecules of RNA, by initially converting the RNA into its complementary DNA molecule using the enzyme reverse transcriptase and then following the standard procedure for PCR. It can be used to analyse gene expression in samples taken from certain tissues or under particular conditions. Real-time PCR (RT-PCR) or quantitative PCR (qPCR) is a variant of the technique used for quantitatively estimating amounts of RNA or DNA in a sample. Essentially, it measures the rate of accumulation of DNA through successive cycles of PCR, on the basis that the more target molecules present in the starting sample, the faster is their subsequent amplification. All newly synthesized copies of the target are tagged with a fluorescent marker, and continuous monitoring of the amount of fluorescence indicates the rate of amplification and hence the amount of target molecule in the original sample. See also directed evolution; randomly amplified polymorphic DNA. https://www.dnalc.org/resources/animations/pcr.html Animated account of PCR from the DNA Learning Center
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