ABSTRACT
DNA can be sequenced by the chemical method or the chain termination procedure. Two main methods have been devised to sequence DNA; the chemical method and the chain termination method. The chain termination method is now the method usually used because of its speed and simplicity. In this procedure, the DNA to be sequenced is prepared as a single-stranded molecule so that it can act as a template for DNA synthesis in the sequencing reaction. E. coli DNA polymerase I is used to copy this DNA template. Automated DNA sequencing is commonplace, based on the chain termination method but using a fluorescent dye attached to an oligonucleotide primer instead of using radioactive labeling. Modern automated DNA sequencing systems designed to generate over half a million bases of sequence per day use sequencing gels contained in multiple capillary tubes.
