DNA amplification

The polymerase chain reaction has become a mainstream tool for the molecular biologist. The sensitivity, efficiency, and speed of this method is unparalleled for the amplification and detection of exquisitely minute quantities of nucleic acids. Through repetitive cycles of heat denaturation of samples, followed by the base pairing of primers designed to identify one DNA sequence among the cellular heterogeneity, and finally synthesis of new DNA strands identical to the target, single molecules and individual genes can be detected and subsequently characterized. This method has revolutionized the study of gene organization, structure, and expression, not to mention offering newer, faster, and more economical means for the clinical detection infectious disease. That PCR has been fruitful is undisputed; however, the method is not without shortcomings. Among the major limitations of this method are the absolute requirement for well-designed primers, the super sensitivity of this method to biological contaminants from any of a variety of sources, and subtle, though very important, inter- and intra- laboratory variations in technique.