Postcards From The Hedge

Polymerase Chain Reaction (PCR) is a powerful technique for detecting the presence of nucleic acids of specific sequence - that is, DNA and RNA: polymers that can be viewed as long 'sentences' in an alphabet of four different 'letters'. By running through cycles of sequence duplication, the quantity of the target sequence approximately doubles with each step, generating sufficient from small initial quantities to be analysed by chemical techniques too insensitive to detect the original quantity. Additionally, because it uses sequence-specific ‘primers’ to start the ball rolling, careful design of these permits a very high degree of sequence specificity.  During the Coronavirus pandemic, much internet chatter and mythology has arisen around this technique, which this article will attempt to address. PCR - a rough guide. PCR was invented by Kary Mullis, a chemist at Cetus Corporation, in 1983. This invention earned him the Nobel Prize in Chemistry in 1993.  In biol