DNA sequencing by the Sanger technique makes use of dideoxynucleotides for which of the following reasons?
A) To ensure that DNA is synthesized from only one of the two DNA strands
B) To terminate DNA synthesis at every nucleotide
C) To promote base-pairing between the newly synthesized strand and the template strand
D) To provide sites at which DNA cleavage will occur

Question

Quizplus · Accepted Answer

Dideoxynucleotides lack a 3' OH group that is necessary for the formation of a phosphodiester bond with the next incoming nucleotide during DNA synthesis. Therefore, when incorporated into a growing DNA chain, dideoxynucleotides act as chain terminators, resulting in DNA fragments of varying lengths. This principle is utilized in the Sanger DNA sequencing method, where a mixture of normal and dideoxy nucleotides are used to generate a series of fragments that differ by a single nucleotide, enabling the determination of the DNA sequence by size-based separation.

DNA Sequencing by the Sanger Technique Makes Use of Dideoxynucleotides