Eventually the reactions begin to slow down and stop all together or plateau. Each tube or reaction will plateau at a different point, due to the different reaction kinetics for each sample. These differences can be seen in the plateau phase. The plateau phase is where traditional PCR takes its measurement, also known as end-point detection.
Figure 3 also shows that the three replicate samples, which started out at the same quantity in the beginning of the reaction, reflect different quantities at the plateau phase. Since the samples are replicates they should have identical quantities. Therefore, it will be more precise to take measurements during the exponential phase, where the replicate samples are amplifying exponentially.
The amplification phases can be viewed differently to assess the PCR phases. The figures that follow show the phases of PCR in a Logarithmic scale view and a Linear scale view (Figures 4 and 5). Applied Biosystems Sequence Detection
System Instruments can view the data in both forms.
