In eukaryotic rRNA and tRNA synthesis is catalysed by :

Options

A. RNA polymerase I and DNA polymerase I
B. RNA polymerase II and DNA polymerase II
C. DNA polymerase I and II
D. RNA polymerase I and II

Answer

To solve the question regarding which enzyme catalyzes the synthesis of rRNA and tRNA in eukaryotes, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Types of RNA in Eukaryotes**:
- Eukaryotic cells synthesize three main types of RNA: ribosomal RNA (rRNA), messenger RNA (mRNA), and transfer RNA (tRNA).

2. **Identify the RNA Polymerases**:
- There are three types of RNA polymerases in eukaryotes:
- **RNA Polymerase I**: Primarily responsible for synthesizing rRNA (except for 5S rRNA).
- **RNA Polymerase II**: Responsible for synthesizing mRNA and some small nuclear RNAs.
- **RNA Polymerase III**: Responsible for synthesizing tRNA, 5S rRNA, and other small RNAs.

3. **Determine the Specific Roles**:
- **rRNA Synthesis**:
- RNA Polymerase I synthesizes the majority of rRNA (28S, 18S, and 5.8S rRNA).
- **tRNA Synthesis**:
- RNA Polymerase III synthesizes tRNA.

4. **Select the Correct Answer**:
- The question asks for the enzymes responsible for the synthesis of both rRNA and tRNA in eukaryotes.
- From the analysis:
- **rRNA** is synthesized by **RNA Polymerase I**.
- **tRNA** is synthesized by **RNA Polymerase III**.

5. **Final Conclusion**:
- Therefore, the correct answer is:
- **Ribosomal RNA (rRNA) is synthesized by RNA Polymerase I**.
- **Transfer RNA (tRNA) is synthesized by RNA Polymerase III**.

### Answer:
- **Ribosomal RNA (rRNA) is synthesized by RNA Polymerase I.**
- **Transfer RNA (tRNA) is synthesized by RNA Polymerase III.**