Tailoring of hnRNa is done by

Options

A. Snurps
B. Introns
C. Exons
D. 18 SrRNA

Answer

### Step-by-Step Solution:

1. **Understanding hnRNA**:
- hnRNA stands for heterogeneous nuclear RNA. It is the precursor to mRNA and contains both introns and exons.

2. **Role of snRNPs**:
- The tailoring or processing of hnRNA involves the removal of introns and the joining of exons. This process is facilitated by small nuclear ribonucleoproteins (snRNPs).

3. **Composition of snRNPs**:
- snRNPs are complexes made up of small nuclear RNA (snRNA) and proteins. They play a crucial role in the splicing process.

4. **Function of snRNA**:
- The small nuclear RNA within snRNPs is about 150 nucleotides long and is essential for the splicing mechanism. It helps in recognizing the splice sites on the hnRNA.

5. **Enzymatic Activity**:
- The snRNPs, through their snRNA components, activate the enzymatic activity required for splicing, which ultimately tailors the hnRNA into mature mRNA.

6. **Conclusion**:
- Therefore, the tailoring of hnRNA is primarily done by snRNPs (small nuclear ribonucleoproteins).

### Final Answer:
The tailoring of hnRNA is done by snRNPs (small nuclear ribonucleoproteins).

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