Question

It is common to use ddNTPs (dideoxynucleoside triphosphates) for sequencing DNA because, when incorporated into a growing DNA polymer, the ddNTP acts as a chain terminator, allowing the researcher an opportunity to determine the last-added base to a given chain. From your knowledge of nucleotide structure and DNA synthesis, what is the most likely attribute of ddNTPs for DNA sequencing?
A. The ddNTPs lack a 5′ carbon.

B. The ddNTPs lack a 3′ hydroxyl group.

C. The ddNTPs lack a nitrogenous base.

D. The ddNTPs lack the sugar component.

Answer 1

Answer:

B. The ddNTPs lack a 3′ hydroxyl group.

Explanation:

Dideoxynucleotides is a family of inhibitors of the DNA polymerase, its official name is 2',3' dideoxynucleotides but they are commonly called ddNTPs. One of the main characteristics of this compound is the absence of the 3'-hydroxyl group in the deoxyribose, due to the absence of this group, it is impossible to form a phosphodiester bond between nucleotides and the DNA synthesis is stopped.