Up to Speed on PCR

Real-time PCR Systems

Cepheid's Smart Cycler System

PCR--a technique so common in today's laboratories that it is easy to forget its revolutionary impact--enables the specific amplification and detection of as little as a single copy of a particular nucleotide sequence. However, PCR has the potential to be used not just for the detection of specific sequences, but also for their quantification, because of the quantitative relationship between the amount of starting target sequence and the amount of PCR product at any given cycle that falls within the reaction's exponential range.

The theory is straightforward, but a number of technical caveats are associated with the use of conventional end-point methodologies for quantitative PCR.^1,2 In these techniques, PCR results are monitored after a given number of cycles, by which point factors such as limiting reagent concentrations and side reactions may have played a significant role in affecting final product concentration. Quantitative...