Qualitative and Quantitative PCR: A Technical Overview

The nature of the polymerase chain reaction (PCR) process lends itself well to qualitative determinations. It transforms very small quantities of analyte into the realms of bucket chemistry, allowing specific gene portions to be directly visualized with ethidium bromide and ultraviolet light. It was these approaches that were first to be exploited in DNA analysis. The early PCR tests were for the presence or absence of a gene, transcript, or by inference whole organism (e.g., pathogen identification). These qualitative tests rapidly evolved to distinguish between related genes or organisms and accelerated the whole process of molecular taxonomy.