Organelle ribosomes occur in

Options

A. Bacteria
B. Blue-Green Algae
C. Plastids and Mitochondria
D. Nucleus

Answer

**Step-by-Step Solution:**

1. **Understanding Ribosomes**: Ribosomes are cellular structures that serve as the site of protein synthesis. They are often referred to as the "protein factories" of the cell.

2. **Composition of Ribosomes**: Ribosomes are made up of ribonucleic acids (RNA) and proteins. This composition is crucial for their function in translating messenger RNA (mRNA) into proteins.

3. **Location of Ribosomes**: Ribosomes can be found in various locations within a cell:
- In the cytoplasm of prokaryotic cells (like bacteria).
- On the rough endoplasmic reticulum (RER) in eukaryotic cells.
- In organelles such as chloroplasts (plastids) and mitochondria.

4. **Analyzing the Options**:
- **A. Bacteria**: Ribosomes are present in bacteria, as they are prokaryotic cells.
- **B. Blue Green Algae**: Blue-green algae (cyanobacteria) also contain ribosomes.
- **C. Plastids and Mitochondria**: Both plastids (like chloroplasts) and mitochondria have their own ribosomes, which are similar to prokaryotic ribosomes.
- **D. Nucleus**: Ribosomes are not located in the nucleus itself; however, ribosomal RNA is synthesized there.

5. **Conclusion**: The question asks where ribosomes occur. While ribosomes are present in bacteria and blue-green algae, the most specific answer that includes organelles is option C, which states that ribosomes occur in plastids and mitochondria.

**Final Answer**: C. Plastids and Mitochondria

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