Question

How is the nucleotide different from a nucleoside?

• A. Nitrogen base
• B. Phosphate group
• C. Sugar
• D. Hydrogen bond

Hint:

Remember the relation: \[ \boxed{ \text{Nucleoside} +\text{Phosphate} = \text{Nucleotide} } \] Examples: \[ \boxed{ \begin{aligned} \text{Adenosine} &\rightarrow \text{Nucleoside}\\ \text{AMP (Adenosine Monophosphate)} &\rightarrow \text{Nucleotide} \end{aligned} } \] The phosphate group is the key difference between a nucleoside and a nucleotide.

Answer 1

The Correct Option is B

Concept: Nucleosides and nucleotides are the fundamental units of nucleic acids. A nucleoside consists of: \[ \boxed{\text{Nitrogenous base}+\text{Pentose sugar}} \] A nucleotide consists of: \[ \boxed{\text{Nitrogenous base}+\text{Pentose sugar}+\text{Phosphate group}} \] Thus, a nucleotide differs from a nucleoside by the presence of one or more phosphate groups.

Step 1: Understand the composition of a nucleoside.
A nucleoside contains two components: \[ \boxed{ \begin{aligned} &\text{Nitrogenous base}\\ +&\text{Pentose sugar} \end{aligned} } \] The base is attached to the sugar by a glycosidic bond.

Step 2: Understand the composition of a nucleotide.
A nucleotide consists of: \[ \boxed{ \begin{aligned} &\text{Nitrogenous base}\\ +&\text{Pentose sugar}\\ +&\text{Phosphate group} \end{aligned} } \] The phosphate group is attached to the sugar through a phosphoester bond.

Step 3: Identify the distinguishing feature.
The only additional component present in a nucleotide is the phosphate group. Hence, \[ \boxed{ \text{Nucleotide} = \text{Nucleoside} + \text{Phosphate group}. } \] Therefore, \[ \boxed{\textbf{Option (B)}} \] is the correct answer.