What phase of PCR is analyzed for standard PCR?

The phase of PCR that is primarily analyzed is the exponential phase. During this phase, the amount of DNA is doubling with each cycle of the PCR process, leading to a rapid increase in the target DNA concentration. This phase is crucial because it is where the reaction efficiency is highest, and the amplification of the target sequence reflects a near-perfect doubling of DNA, which allows for accurate quantification. The analysis of data from this phase allows researchers to discern the presence and quantity of the target DNA effectively, as the signal corresponds directly to the reaction's efficiency and the initial amount of template DNA.

The logarithmic or log phase often refers to the overall growth phase characterized by a steady increase in product, but it is not as commonly used as a specific term in the analysis context as the exponential phase. The stationary phase occurs when the reaction components become limiting, and no further amplification takes place, which does not yield useful data for analysis. The declining phase signifies a drop in the efficiency of amplification due to depletion of reagents or accumulation of products, making it unsuitable for analysis. Thus, the exponential phase remains the focus for interpreting results in standard PCR.