Modern-day DNA sequencing techniques, such as Sanger sequencing, are based on chain termination. Chain termination methods rely on the use of deoxynucleotide triphosphates (dNTPs) and labeled dideoxynucleotide
Modern-day DNA sequencing techniques, such as Sanger sequencing, are based on chain termination. Chain termination methods rely on the use of deoxynucleotide triphosphates (dNTPs) and labeled dideoxynucleotide triphosphates (ddNTPs) in a reaction with a DNA polymerase and a primer to make a duplicate copy of the DNA to be sequenced. The incorporation of ddNTPs to the growing strand prevents the addition of subsequent dNTPs, thus stopping the actively elongating DNA molecule, and resulting in a labeled ddNTP at the end of each DNA fragment. The sequence of nucleotides can be determined by separating the DNA products by size. Current sequencing methods based on Sanger sequencing involve the use of fluorescently-labeled ddNTPs where each base is labeled with a unique fluorophore.