DNA AMPLIFICATION

The polymerase chain reaction has become a mainstream tool for the mol ecular biologist. The sensitivity, efficiency, and speed of this metho d is unparalleled for the amplification and detection of exquisitely m inute quantities of nucleic acids. Through repetitive cycles of heat d enaturation of samples, followed by the base pairing of primers design ed to identify one DNA sequence among the cellular heterogeneity, and finally synthesis of new DNA strands identical to the target, single m olecules and individual genes can be detected and subsequently charact erized. 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 w ithout shortcomings. Among the major limitations of this method are th e absolute requirement for well-designed primers, the super sensitivit y of this method to biological contaminants from any of a variety of s ources, and subtle, though very important, inter- and intra-laboratory variations in technique.