Sanger method is one of the most reliable and earliest DNA sequencing methods. DNA is synthesized from four deoxynucleotide triphosphates (dNTPs). Each new nucleotide is added to the 3€² -OH group of the last dNTP added. Dideoxythymidine triphosphates (ddTTPs) can be added to the growing DNA strand but when it is, chain elongation stops because there is no 3€² -OH for the next nucleotide to be attached to. The DNA to be sequenced is prepared as a single strand. This template DNA is supplied with a mixture of dATP, dGTP, dCTP and dTTP in ample quantities. A mixture of all four dideoxynucleotides (ddATP, ddGTP, ddCTP and ddTTP), each present in limiting quantities and each labeled with a tag" that fluoresces a different color