Nucleoside from one of the precursor in the formation of the genetic material within the living system . What is the composition of nucleoside ?

Options

A. Five carbon sugar molecule , nitrogen base only
B. Six carbon sugar molecule , nitrogen base only
C. Six carbon sugar molecule , nitrogen base and phosphate group only
D. Five carbon sugar molecule , nitrogen base , and amino acids only

Answer

To determine the composition of a nucleoside, let's break down the information step by step:

### Step 1: Understanding Nucleosides
A nucleoside is a molecular structure that forms the basic building block of nucleic acids, such as DNA and RNA. It is essential to distinguish between nucleosides and nucleotides.

### Step 2: Components of a Nucleoside
A nucleoside is composed of two main components:
1. **5-Carbon Sugar**: This sugar can either be ribose (in RNA) or deoxyribose (in DNA).
2. **Nitrogen Base**: This can be one of the four bases: adenine (A), guanine (G), cytosine (C), or thymine (T) in DNA, and uracil (U) replaces thymine in RNA.

### Step 3: Identifying the Correct Option
From the options given:
- **Option 1**: 5-Carbon sugar molecule and Nitrogen base only. (This is correct)
- **Option 2**: 6-Carbon sugar molecule and nitrogen base only. (Incorrect, as nucleosides contain 5-carbon sugars)
- **Option 3**: 6-Carbon sugar molecule, nitrogen base, and phosphate group only. (Incorrect, as nucleosides do not contain a phosphate group)
- **Option 4**: 5-Carbon sugar molecule, nitrogen base, and phosphate group. (Incorrect, as this describes a nucleotide, not a nucleoside)

### Conclusion
The correct answer is **Option 1**: A nucleoside is composed of a 5-carbon sugar molecule and a nitrogen base only.