Question

Which of the following represents nucleoside?

• A.

  

• B.

  

• C.

  

• D.

  

Hint:

- Nucleosides are composed of a sugar and a nitrogenous base, while nucleotides include one or more phosphate groups in addition to these two components.

Answer 1

The Correct Option is C

Step 1: Understand the definition of a nucleoside.
A nucleoside is a biochemical compound that consists of a nitrogenous base (either purine or pyrimidine) linked to a sugar molecule (ribose or deoxyribose). Crucially, nucleosides do not contain any phosphate groups. When a phosphate group is added to a nucleoside, it becomes a nucleotide.
Step 2: Identify the components in the given options.
Option (1) contains a phosphate group, so it represents a nucleotide, not a nucleoside.
Option (2) also contains a phosphate group, making it a nucleotide.
Option (3) does not contain a phosphate group, consisting only of the sugar and the nitrogenous base. Therefore, it correctly represents a nucleoside.
Option (4) contains only the sugar molecule and is missing both the nitrogenous base and phosphate group. Therefore, it is not a nucleoside.
Step 3: Conclude the correct answer.
Based on the analysis in Step 2, Option (3) is the correct answer because it is the only structure that fits the definition of a nucleoside, consisting only of a sugar and a nitrogenous base. Thus, the correct answer is (3).