The smallest RNA is :-

Options

A. tRNA
B. mRNA
C. rRNA
D. genetic RNA

Answer

To determine the smallest RNA, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Types of RNA**:
- There are three main types of RNA:
- Ribosomal RNA (rRNA)
- Messenger RNA (mRNA)
- Transfer RNA (tRNA)

2. **Analyze the Abundance of Each Type**:
- Ribosomal RNA (rRNA) is the most abundant, making up about 70-80% of total RNA.
- Messenger RNA (mRNA) is the least abundant, constituting only about 2-3% of total RNA.
- Transfer RNA (tRNA) accounts for approximately 13-18% of total RNA.

3. **Determine the Size of Each RNA Type**:
- Among these, tRNA is known to be the smallest in terms of nucleotide length and molecular weight.

4. **Additional Characteristics of tRNA**:
- tRNA is also referred to as soluble RNA (sRNA).
- It is transcribed by RNA polymerase III.
- The structure of tRNA can be represented in two models:
- The 2D cloverleaf model, described by R. Holley.
- The 3D L-shaped model, described by Kim.

5. **Conclusion**:
- Based on the analysis, the smallest RNA is tRNA.

### Final Answer:
The smallest RNA is tRNA (transfer RNA).

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