Polymerase chain reaction
"Polymerase chain reaction": A method for the multiplication of a defined DNA section.
The American Kary Mullis developed PCR in the mid-1980s and was awarded the Nobel Prize for Chemistry in 1993. It is the basis of molecular biological research, but also for the diagnosis of pathogens, including the monitoring of antiviral therapies and DNA analyses in forensic medicine for the investigation of traces and the determination of paternity.For DNA amplification, the double strand is separated into the two single strands by the effect of heat, and in the subsequent cooling phase, start molecules bind to the individual strands. They mark the start of replication. A heat-stable bacterial DNA polymerase now completes the individual DNA strands back into double helices when heated to 72 °C with the help of added nucleotide fragments. The repetition of this reaction sequence - PCR cycles - is controlled by the temperature curve. This allows DNA segments to be multiplied exponentially in just a few hours.
However, this also requires extremely clean work, as any contamination with traces of unwanted DNA is also amplified!