Non-membranous nucleoplasmic structures in nucleus are the site for active synthesis of

Options

A. Protein synthesis
B. mRNA
C. rRNA
D. tRNA

Answer

To answer the question regarding the non-membranous nucleoplasmic structures in the nucleus and their role in active synthesis, we can follow these steps:

### Step-by-Step Solution:

1. **Identify Non-Membranous Structures**: The primary non-membranous structure in the nucleus is the nucleolus. It is distinct from other nuclear components because it lacks a surrounding membrane.

2. **Function of the Nucleolus**: The nucleolus is primarily involved in the synthesis of ribosomal RNA (rRNA). It plays a crucial role in assembling ribosomal subunits, which are essential for protein synthesis.

3. **Different Types of RNA**:
- **mRNA (messenger RNA)**: This is synthesized in the nucleus but not specifically in the nucleolus. It is produced from DNA during transcription and then transported to the cytoplasm for protein synthesis.
- **tRNA (transfer RNA)**: While tRNA is also synthesized in the nucleus, its final processing occurs in the cytoplasm.
- **rRNA (ribosomal RNA)**: This is synthesized in the nucleolus and is a key component of ribosomes.

4. **Conclusion**: Given that the question asks for the site of active synthesis within the non-membranous nucleoplasmic structures, the correct answer is rRNA, as it is actively synthesized in the nucleolus.

### Final Answer:
Non-membranous nucleoplasmic structures in the nucleus are the site for active synthesis of **rRNA (ribosomal RNA)**.

---