To briefly highlight the topics of this lesson, remember that PCR is a relatively easy lab technique which amplifies the amount of DNA present, much like living cells do in the beginning stages of a cell cycle. There are 5 chemical components of a PCR reaction: a DNA template, a DNA polymerase, primers, nucleotides, and a buffer. The 3 temperature steps for one cycle are the denaturation, primer annealing and extension steps. There are now many variations and uses of PCR ranging from forensics to genomic studies to identifying transgenic crops. PCR can be very useful for determining whether or not a plant contains a transgene.