Overview of qPCR

Learn how qPCR differs from traditional PCR by monitoring DNA amplification in real-time through fluorescence signal increases as the reaction progresses, rather than analyzing results only at completion.

Recognize the two main approaches for monitoring qPCR: SYBR Green I dye that binds to double-stranded DNA, and probe-based assays like TaqMan that use target-specific probes with fluorophore-quencher pairs.

Learn how TaqMan assays work: the 5-prime endonuclease domain of Taq polymerase cleaves a target-specific probe, separating the fluorophore from the quencher and generating an amplification-dependent fluorescence increase.

Use a thermocycler coupled with a fluorometer to modulate reaction temperature during DNA amplification while simultaneously monitoring the fluorescence signal at each PCR cycle to generate a real-time qPCR curve.

Interpret the four distinct phases of the amplification curve: lag phase (weak signal), exponential phase (used for quantification with strong signal), linear phase, and plateau phase.

Identify the quantification cycle (Cq) value when fluorescent signal becomes detectable above background, then use Cq values to evaluate relative target abundance between samples or calculate absolute quantities using a standard curve.

Recognize that qPCR can be modified to detect and quantify RNA targets in addition to DNA.

Ensure proper experimental design and data analysis by consulting the MIQE guidelines, which establish standards for consistent qPCR methodology and reporting appropriate for peer-reviewed publication.