what does pcr do
PCR amplifies a specific region of a DNA strand (the DNA target). Most PCR methods typically amplify DNA fragments of between 0.1 and 10 kilo base pairs (kbp), although some techniques allow for amplification of fragments up to 40 kbp in size. Digital PCR (dPCR) : used to measure the quantity of a target DNA sequence in a DNA sample. 2  The DNA sample is highly diluted so that after running many PCRs in parallel, some of them do not receive a single molecule of the target DNA. 3  The target DNA concentration is calculated using the proportion of negative outcomes.