Rough ER is associated with

Options

A. Ribosomes
B. Nucleus
C. Mesosomes
D. Peroxysomes

Answer

### Step-by-Step Solution:

1. **Understanding Endoplasmic Reticulum (ER)**:
- The endoplasmic reticulum (ER) is a large internal membrane system within the cell. It plays a crucial role in the synthesis and processing of proteins and lipids.

2. **Types of Endoplasmic Reticulum**:
- There are two types of endoplasmic reticulum:
- **Rough Endoplasmic Reticulum (RER)**: Characterized by the presence of ribosomes on its cytoplasmic surface.
- **Smooth Endoplasmic Reticulum (SER)**: Lacks ribosomes and is involved in lipid synthesis and detoxification processes.

3. **Role of Ribosomes**:
- Ribosomes are the cellular structures responsible for protein synthesis. They can be found either free-floating in the cytoplasm or attached to the rough endoplasmic reticulum.

4. **Association of Rough ER**:
- The rough endoplasmic reticulum is specifically associated with ribosomes. This association is what gives it the "rough" appearance under a microscope.

5. **Conclusion**:
- Therefore, the rough endoplasmic reticulum is associated with ribosomes, which are essential for the synthesis of proteins.

### Final Answer:
The rough endoplasmic reticulum is associated with **ribosomes**.

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