Introduction and Historical Overview of DNA Sequencing

Abstract

The process of DNA sequencing has made tremendous strides in throughput, improved accuracy, ease of production, and lowered cost. As the practice of DNA sequencing has improved, so has the downstream data analysis with sophisticated databases and bioinformatics tools. Together, these advances have enlarged the number of applications upon which DNA sequencing can be brought to bear. This introductory unit provides a description of DNA sequencing with a focus on current and "NextGen" (second and third generation) automated technologies and applications. Supplement 96 Figure 7.0.2 General strategy for DNA sequencing.To sequence a fragment of DNA, a set of radiolabeled single-stranded oligonucleotides is generated in four separate reactions. In each of the four reactions, the oligonucleotides have one fixed end and one end that terminates sequentially at each A, T, G, or C, respectively. The products of each reaction are fractionated by electrophoresis on adjacent lanes of a high-resolution polyacrylamide gel. After autoradiography, the DNA sequence can be "read" directly from the gel.