70S ribosomes are seen in

Options

A. Mitochondria
B. Bacterial cell
C. ER
D. Both A and B

Answer

To solve the question "70S ribosomes are seen in," we will analyze the options provided and determine where 70S ribosomes are found.

### Step-by-Step Solution:

1. **Understand Ribosomes**:
- Ribosomes are cellular structures responsible for protein synthesis. They are often referred to as "protein factories."

2. **Types of Ribosomes**:
- There are two main types of ribosomes based on the type of cell:
- **Prokaryotic ribosomes**: These are 70S ribosomes.
- **Eukaryotic ribosomes**: These are 80S ribosomes.

3. **Identify the Options**:
- The options given are:
- A) Mitochondria
- B) Bacterial cell
- C) Endoplasmic reticulum
- D) Both A and B

4. **Analyze Each Option**:
- **Mitochondria**:
- Mitochondria are organelles found in eukaryotic cells, but they contain 70S ribosomes similar to those found in prokaryotic cells.
- **Bacterial Cell**:
- Bacteria are prokaryotic organisms, and they also contain 70S ribosomes.
- **Endoplasmic Reticulum**:
- The endoplasmic reticulum is a eukaryotic organelle that contains 80S ribosomes, not 70S.

5. **Conclusion**:
- Based on the analysis, 70S ribosomes are present in both mitochondria and bacterial cells. Therefore, the correct answer is:
- **Option D: Both A and B**.

### Final Answer:
70S ribosomes are seen in both mitochondria and bacterial cells (Option D).

---