Widely used method of DNA sequencing; uses single-stranded template DNA and short complementary primer that is annealed and extended by DNA polymerase. Reaction product is then split into 4 tubes (A, C, G, and T), each containing low concentration of indicated dideoxynucleotide along with normal deoxynucleotides. Dideoxynucleotides block further chain extension, and each tube contains mixture of chains determined by template sequence. Material in tubes is then denatured and run on acrylamide sequencing gel and bands are read.