In genetic engineering, after the creation of recombinant DNA, it has to be transferred into the host using a vector. Which of the following agents can be used as a vector?
A. pBR322
B. E.coli
C. Transposons
D.Mosquito
E. A disarmed Ti plasmid

Options

A. A, C, and E
B. A , B , and E
C. A , B , and C
D. A, B, C , D and E

Answer

To solve the question regarding which agents can be used as vectors in genetic engineering, we will analyze each option provided.

### Step-by-Step Solution:

1. **Understanding Vectors in Genetic Engineering**:
- Vectors are DNA molecules used to deliver genetic material into cells. They are essential for the transfer of recombinant DNA into host organisms.

2. **Analyzing Option A: pBR322**:
- pBR322 is a plasmid vector derived from E. coli. It is designed for cloning and has features such as an origin of replication (ORI) and selectable markers (antibiotic resistance genes). This allows for the identification of successfully transformed cells.
- **Conclusion**: **pBR322 can be used as a vector.**

3. **Analyzing Option B: E. coli**:
- E. coli is a bacterium, not a vector itself. While it can be used as a host for plasmids, it does not serve as a vector for transferring recombinant DNA.
- **Conclusion**: **E. coli cannot be used as a vector.**

4. **Analyzing Option C: Transposons**:
- Transposons are mobile genetic elements that can move within and between genomes. They can carry DNA sequences and integrate them into the host genome, making them useful for gene transfer.
- **Conclusion**: **Transposons can be used as a vector.**

5. **Analyzing Option D: Mosquito**:
- Mosquitoes are living organisms and not suitable as vectors for recombinant DNA technology. The concept of inserting DNA into a mosquito's genome for the purpose of genetic engineering is not practical in this context.
- **Conclusion**: **Mosquito cannot be used as a vector.**

6. **Analyzing Option E: A disarmed Ti plasmid**:
- The Ti (tumor-inducing) plasmid from Agrobacterium tumefaciens is used in plant genetic engineering. When disarmed (removing the tumor-inducing capability), it can still transfer genes into plant cells effectively.
- **Conclusion**: **A disarmed Ti plasmid can be used as a vector.**

### Final Answer:
The agents that can be used as vectors in genetic engineering are:
- **A. pBR322**
- **C. Transposons**
- **E. A disarmed Ti plasmid**

Thus, the correct answer is **A, C, and E**.