Use in clinical context
The polymerase chain reaction (PCR) is a widely used laboratory method to generate copies of DNA. Many genomic tests require more DNA than can be extracted from cells themselves, and so by performing a PCR, enough DNA can be produced for the specific test. In whole genome sequencing it is used in the library-preparation phase of DNA sequencing. PCR makes use of the semi-conservative replication properties of DNA in which the DNA helix is ‘unzipped’, and each strand acts as a template to build a new strand of DNA. By artificially recreating this process and repeating it a number of times, lots of copies of the template DNA are produced.