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Polymerase Chain Reaction and Other Amplification Systems

Nucleic Acids Structure and Mapping

  1. Theodore K. Christopoulos

Published Online: 15 SEP 2006

DOI: 10.1002/9780470027318.a1424

Encyclopedia of Analytical Chemistry

Encyclopedia of Analytical Chemistry

How to Cite

Christopoulos, T. K. 2006. Polymerase Chain Reaction and Other Amplification Systems. Encyclopedia of Analytical Chemistry. .

Author Information

  1. University of Patras, Patras, Greece

Publication History

  1. Published Online: 15 SEP 2006


The discovery of restriction endonucleases is perhaps the most significant technical milestone in the development of recombinant DNA technology. For, together with ligation and transformation procedures, they enabled the insertion of genes of any organism in suitable vectors (e.g. plasmids), introduction of the vector in bacteria and subsequent replication of the DNA of interest during cell division (cloning). Other important technical milestones include the development of methods for DNA sequencing and the chemical synthesis of oligodeoxynucleotides.

The polymerase chain reaction (PCR) is another technique which had a major impact in every area of research that involves nucleic acid analysis. PCR is a method of exponentially increasing the concentration of a specific nucleic acid sequence in a reaction mixture. A great advantage of PCR is that the target nucleic acid does not need to be particularly pure. It can be a minute part of an extremely complex mixture of biological material. Crude cell lysates provide a very good starting material. The ability to propagate, in a few hours, minute amounts of DNA that are too small for standard amplification (i.e. cloning) techniques gives PCR an extraordinary power and sensitivity.

The advent of PCR stimulated the research activity in the development of alternative exponential amplification systems such as the ligase chain reaction (LCR), the self-sustained sequence replication (3SR), the nucleic acid sequence-based amplification (NASBA) and the strand displacement amplification system (SDA). An essential feature of target amplification techniques is that the amplification is an iterative process consisting of successive cycles. The products synthesized in one cycle act as templates for the next cycle.

Amplification techniques can be used to amplify trace amounts of nucleic acid sequences in blood, cells, water, food and other clinical and environmental samples. Fixed tissue specimens, buccal cells from mouth washes, human hair, dried blood at the scene of a crime, single lymphoid or sperm cells are examples of starting material that may be used for nucleic acid analysis.