Which of the following is / are vectors for cloning in the eukaryotic organisms ?
I. Plasmid
II. Bacteriophages
III. Ti plasmid
IV. Disarmed retrovirus.

Options

A. I and II
B. II and III
C. I, II and III
D. All of these

Answer

To determine which of the following options are vectors for cloning in eukaryotic organisms, let's analyze each option step by step.

### Step 1: Understanding Cloning Vectors
Cloning vectors are DNA molecules used to transport foreign genetic material into another cell. They must have the ability to replicate within the host organism.

### Step 2: Analyzing Each Option
1. **Plasmid**:
- Plasmids are circular DNA molecules found in bacteria. They can replicate independently of chromosomal DNA and can carry foreign DNA into host cells.
- **Conclusion**: Plasmids are cloning vectors.

2. **Bacteriophages**:
- Bacteriophages are viruses that infect bacteria. They can also be engineered to carry foreign DNA and can replicate within bacterial cells.
- **Conclusion**: Bacteriophages are cloning vectors, but they primarily target prokaryotic cells.

3. **Ti Plasmid**:
- Ti plasmid (Tumor-inducing plasmid) is found in Agrobacterium tumefaciens, a plant pathogen. It can transfer genes into plant cells, making it a useful tool for genetic engineering in plants.
- **Conclusion**: Ti plasmid is a cloning vector for eukaryotic organisms (specifically plants).

4. **Disarmed Retrovirus**:
- Retroviruses can integrate their genetic material into the host genome. Disarmed retroviruses are engineered to remove pathogenic properties while retaining the ability to deliver genes into animal cells.
- **Conclusion**: Disarmed retroviruses are cloning vectors for eukaryotic organisms (specifically animals).

### Step 3: Final Conclusion
Since all four options (I, II, III, IV) can be utilized as cloning vectors in eukaryotic organisms, the correct answer is:
**All of the above (Option D)**.