Which of the following r-RNAs acts as structural RNA as well as ribozyme in bacteria ?

Options

A. (a) 5 S rRNA
B. (b) 18 S rRNA
C. (c) 23 S rRNA
D. (d) 5.8 S rRNA

Answer

To solve the question "Which of the following r-RNAs acts as structural RNA as well as ribozyme in bacteria?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Role of rRNA**:
- rRNA (ribosomal RNA) is a type of non-coding RNA that plays a crucial role in the structure and function of ribosomes, which are essential for protein synthesis.

2. **Identify the Functions of rRNA**:
- rRNA serves as structural RNA, forming the core of ribosome structure.
- Certain rRNAs also exhibit enzymatic activity, acting as ribozymes. In the context of ribosomes, they can catalyze the formation of peptide bonds between amino acids.

3. **Analyze the Options**:
- **Option A: 5S rRNA**: This rRNA is part of the larger subunit in eukaryotes, not bacteria. Therefore, it cannot be the answer.
- **Option B: 18S rRNA**: This rRNA is found in the smaller subunit of eukaryotic ribosomes, making it incorrect for bacteria.
- **Option C: 23S rRNA**: This rRNA is part of the larger subunit of prokaryotic ribosomes (bacteria) and has ribozyme activity, making it a strong candidate for the answer.
- **Option D: 5.8S rRNA**: Similar to 5S rRNA, this is also part of the larger subunit in eukaryotes, thus it is not applicable to bacteria.

4. **Conclusion**:
- After analyzing all options, **Option C: 23S rRNA** is the correct answer as it acts as both structural RNA and ribozyme in bacteria.

### Final Answer:
**C: 23S rRNA**