In RNA, which type of nitrogen base is not present as a structural component :-

Options

A. Uracil
B. 5-methyl uracil
C. Cytosine
D. Adenine

Answer

To solve the question regarding which type of nitrogen base is not present as a structural component in RNA, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of RNA:**
- RNA, or ribonucleic acid, is composed of nucleotides. Each nucleotide consists of a nitrogenous base, a ribose sugar, and a phosphate group.

2. **Identify the Nitrogenous Bases in RNA:**
- The nitrogenous bases found in RNA are:
- **Purines:** Adenine (A) and Guanine (G)
- **Pyrimidines:** Cytosine (C) and Uracil (U)

3. **Analyze the Options Given:**
- The options provided are:
- Uracil
- 5-methyl uracil
- Cytosine
- Adenine

4. **Determine Which Base is Not Present:**
- Among the options:
- **Uracil** is a nitrogenous base present in RNA.
- **Cytosine** is also present in RNA.
- **Adenine** is present as well.
- **5-methyl uracil** is a derivative of uracil and is not found in the structure of RNA.

5. **Conclusion:**
- Therefore, the nitrogen base that is not present as a structural component in RNA is **5-methyl uracil**.

### Final Answer:
The correct option is **5-methyl uracil**.

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