Question

A nucleoside is formed of
A. Pentose sugar, phosphate and nitrogen base
B. Phosphate and nitrogen base
C. Pentose sugar and phosphate
D. Pentose sugar and nitrogen base

Answer 1

Hint: Nucleic acids are long series like particles formed of a group of nearly the same building blocks termed nucleotides. Each nucleotide consists of a nitrogen-containing pungent base connected to a pentose (five-carbon) sugar, which is in turn connected to a phosphate group.

Complete Answer:
Let us analyse the given options to find the correct answer.
Option A: The nucleotide is the fundamental part of nucleic acids. They are formed of nucleosides and phosphate groups. A nucleoside is formed of a pentose sugar and nitrogen base. Pentose sugars are deoxyribose and ribose. Nitrogen bases are pyrimidines and purines. Therefore this is an incorrect answer.

Option B: Phosphate and nitrogen base cannot form a nucleic acid. Therefore this is an incorrect option.

Option C: Pentose sugar and phosphate cannot form a nucleic acid, therefore this is an incorrect option.

Option D: The sugars which are seen in the nucleotide are ribose or deoxyribose. The nitrogenous bases are pyrimidines and purines. The phosphate is already phosphoric acid. The nucleotide is made by the union of a phosphate combination with a nucleoside. A nucleoside comprises a sugar particle along with an essential nitrogenous base. Therefore this is the correct answer.

Thus option D is the correct answer.

Note: Nucleosides are essential biological particles that work as signalling particles and as precursors to nucleotides required for DNA and RNA synthesis. Synthetic nucleoside analogues are utilized clinically to manage a range of tumours and viral diseases.