Question

The technique of Sanger sequencing takes advantage of the fact that dideoxynucleotides (nucleotides in which the 3′ hydroxyl group is absent) act as:
a) palindromic sites.
b) restriction sites.
c) chain terminators.
d) probes.
e) None of the other answer options is correct.

Answer 1

Ans.

The Sanger sequencing or chain-termination method for sequencing involves use of ddNTPs (dideoxyribonucleotide triphosphates) to identify the sequence of nucleotides in a DNA segment. The ddNTPs are nucleotide derivatives that lack both the 2'- and 3'-hydroxyl group, hence called dideoxyribonucleotides. When a ddNTP is added to a growing chain of DNA, absence of 3'-hydroxyl group leads to termination of growing chain as this ddNTP cannot make phosphodiester bond with a NTP and DNA sequence can be identified.

Thus, the correct answer is option C).