Which of the following are used as vectors

Options

A. Bacterial plasmids
B. Yeast plasmids
C. Some bacteriophages
D. All

Answer

To determine which of the given options are used as vectors, we need to analyze each option provided:

1. **Understanding Vectors**:
- Vectors are vehicles used to transfer genetic material into a host cell. They can be plasmids, viruses, or other methods that facilitate the introduction of DNA into cells.

2. **Analyzing the Options**:
- **Option A: Bacterial Plasmids**:
- Bacterial plasmids are circular DNA molecules found in bacteria that can replicate independently of chromosomal DNA. They are commonly used as vectors in genetic engineering to transfer genes into bacterial cells.
- **Conclusion**: Bacterial plasmids are indeed vectors.

- **Option B: Yeast Plasmids**:
- Yeast plasmids are similar to bacterial plasmids but are used in yeast cells. They can also carry foreign DNA and are used in yeast for gene cloning and expression.
- **Conclusion**: Yeast plasmids are also vectors.

- **Option C: Some Bacteriophages**:
- Bacteriophages are viruses that infect bacteria. Certain bacteriophages can be engineered to carry foreign DNA and deliver it into bacterial cells, making them effective vectors.
- **Conclusion**: Some bacteriophages can act as vectors.

3. **Final Conclusion**:
- Since all three options (bacterial plasmids, yeast plasmids, and some bacteriophages) are used as vectors, the correct answer is **Option D: All of the above**.

### Summary of the Solution:
- **Bacterial plasmids** are vectors.
- **Yeast plasmids** are vectors.
- **Some bacteriophages** are vectors.
- Therefore, the correct answer is **Option D: All of the above**.