Sanger sequencing, also known as chain termination sequencing, is a widely used DNA sequencing method that allows researchers to determine the sequence of nucleotides in a DNA molecule. Modern Sanger sequencing typically uses fluorescently labeled dideoxynucleotides that are detected by a laser after capillary electrophoresis to generate a sequence chromatogram with fluorescent peaks corresponding to incorporation of the four different fluorescent dyes coupled to ddATP, ddCTP, ddGTP, and ddTTP.

In the context of “single direction,” it means that sequencing is performed in one direction along the DNA strand using either the forward or reverse primer of gene of interest.