If we ligate a foreign, DNA at the Barn HI site of tetracycline resistance gene in pBR322 the recombinant plasmid will:

Options

A. Show ampicillin resistance only
B. Show tetracycline resistance
C. Will grow well on tetracycline-containing medium
D. Will not grow on ampicillin-containing medium

Answer

To solve the question about the effects of ligating foreign DNA at the BamHI site of the tetracycline resistance gene in the pBR322 plasmid, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of pBR322**:
- pBR322 is a plasmid that contains two antibiotic resistance genes: one for ampicillin (Amp^R) and one for tetracycline (Tet^R).
- The BamHI site is located within the tetracycline resistance gene.

2. **Ligate Foreign DNA at BamHI Site**:
- When foreign DNA is ligated at the BamHI site of the tetracycline resistance gene, it disrupts the tetracycline resistance gene (Tet^R).
- This means that the plasmid will no longer be able to confer resistance to tetracycline.

3. **Effect on Tetracycline Resistance**:
- Since the tetracycline resistance gene is disrupted, the recombinant plasmid will not be able to grow in a medium containing tetracycline.
- Therefore, the organism containing this recombinant plasmid will die in tetracycline-containing medium.

4. **Effect on Ampicillin Resistance**:
- The ampicillin resistance gene (Amp^R) is located on the other side of the plasmid and is unaffected by the ligation at the BamHI site.
- As a result, the organism will still exhibit resistance to ampicillin.

5. **Evaluate the Options**:
- **Option A**: Show ampicillin resistance only - This is correct because the ampicillin resistance gene remains functional.
- **Option B**: Show tetracycline resistance - This is incorrect because the tetracycline resistance gene is disrupted.
- **Option C**: Will grow well on tetracycline containing medium - This is incorrect as the organism will not survive in this medium.
- **Option D**: Will not grow on ampicillin containing medium - This is incorrect because the organism will still be able to grow in ampicillin due to the intact ampicillin resistance gene.

6. **Conclusion**:
- The correct answer is **Option A**: The recombinant plasmid will show ampicillin resistance only.