Sites of protein synthesis within an eukaryotic cell are

Options

A. Cytoplasm
B. Mitochondria
C. RER
D. All

Answer

**Step-by-Step Solution:**

1. **Identify the Question**: The question asks for the sites of protein synthesis within a eukaryotic cell.

2. **Understanding Protein Synthesis**: Protein synthesis is the process by which cells create proteins. This process involves several key components, including ribosomes, transfer RNA (tRNA), and various cellular structures.

3. **Review the Options**:
- **Option 1: Cytoplasm**: The cytoplasm is indeed a site for protein synthesis. It contains ribosomes and tRNA, which are essential for assembling amino acids into proteins.
- **Option 2: Mitochondria**: Mitochondria have their own ribosomes and can synthesize some proteins independently. Therefore, they are also a site of protein synthesis.
- **Option 3: Rough Endoplasmic Reticulum (RER)**: The RER is studded with ribosomes on its surface, making it a primary site for protein synthesis, especially for proteins that are to be secreted or sent to lysosomes.
- **Option 4: All of the above**: Since all the previous options (cytoplasm, mitochondria, and rough endoplasmic reticulum) are correct sites for protein synthesis, this option is also correct.

4. **Conclusion**: All the given options are correct. The sites of protein synthesis within a eukaryotic cell include the cytoplasm, mitochondria, and rough endoplasmic reticulum.

**Final Answer**: The sites of protein synthesis within a eukaryotic cell are the cytoplasm, mitochondria, and rough endoplasmic reticulum.

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