Ribophorin–I and II occur on the surface of :–

Options

A. Rough E.R.
B. Smooth E.R.
C. Golgi body
D. None

Answer

To answer the question regarding where Ribophorin-I and II occur on the surface, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Ribophorin**: Ribophorin-I and II are proteins that are associated with ribosomes. They play a crucial role in the attachment of ribosomes to the endoplasmic reticulum (ER).

2. **Identifying the Types of Endoplasmic Reticulum**:
- **Rough Endoplasmic Reticulum (RER)**: This type of ER is characterized by the presence of ribosomes on its cytoplasmic surface, giving it a "rough" appearance. It is involved in protein synthesis and processing.
- **Smooth Endoplasmic Reticulum (SER)**: This type lacks ribosomes on its surface, hence it appears smooth. It is primarily involved in lipid synthesis and detoxification processes.

3. **Evaluating the Options**:
- **Option 1: Rough Endoplasmic Reticulum**: This is the correct option because Ribophorin-I and II are found on the surface of the rough ER, where they assist in the binding of ribosomes.
- **Option 2: Smooth Endoplasmic Reticulum**: This option is incorrect as the smooth ER does not have ribosomes on its surface.
- **Option 3: Calci Bodies**: This option is also incorrect. Calci bodies are involved in the packaging of proteins and are not related to ribophorin.
- **Option 4: None**: This option is incorrect as we have identified the rough ER as the correct answer.

4. **Conclusion**: Based on the evaluation of the options, the correct answer is that Ribophorin-I and II occur on the surface of the Rough Endoplasmic Reticulum.

### Final Answer:
Ribophorin-I and II occur on the surface of the Rough Endoplasmic Reticulum.

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