PCR – amplifying DNA by thermal cycling

BiologyBiotechnologyAges 17–18

Each PCR cycle consists of denaturation at 95 °C, primer annealing, and extension at 72 °C, doubling the number of copies of the target DNA segment. Adjust the number of cycles, the annealing temperature relative to the primer's melting temperature, and the initial copy number to see the exponential curve plateau, the gel band brighten, and a nonspecific by-product band appear when annealing temperature is too low — the basis of PCR testing and DNA forensics.