Rough E.R. mainly responsible for :-

Options

A. Protein synthesis
B. cell wall formation
C. Lipid synthesis
D. Cholesterol synthesis

Answer

**Step-by-Step Solution:**

1. **Identify the Structure**: The question refers to the Rough Endoplasmic Reticulum (RER). It is a type of endoplasmic reticulum that is characterized by the presence of ribosomes on its surface.

2. **Understand the Role of Ribosomes**: Ribosomes are small organelles that are attached to the RER. Their primary function is to facilitate protein synthesis.

3. **Protein Synthesis Process**: The process of protein synthesis involves the translation of messenger RNA (mRNA) into a polypeptide chain, which eventually folds into a functional protein. The ribosomes on the RER play a crucial role in this translation process.

4. **Transport of Proteins**: Once proteins are synthesized on the RER, they are packaged and transported to other parts of the cell or outside the cell with the help of the Golgi apparatus.

5. **Conclusion**: Therefore, the main responsibility of the Rough Endoplasmic Reticulum is the synthesis of proteins.

**Final Answer**: Rough E.R. is mainly responsible for protein synthesis.

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