If alien DNA is introduced using Pst I in pBR322 then transformant will grow on :

Options

A. Ampicillin
B. Tetracyline
C. Both (A) and (B)
D. None of these

Answer

To solve the question regarding the growth of transformants when alien DNA is introduced using Pst I in pBR322, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding pBR322**:
- pBR322 is a plasmid that contains genes for antibiotic resistance, specifically to ampicillin and tetracycline.
- It also has a replication origin and multiple restriction sites, including one for the enzyme Pst I.

**Hint**: Identify the features of pBR322 that are relevant to antibiotic resistance and cloning.

2. **Role of Pst I**:
- Pst I is a restriction enzyme that cuts DNA at specific sequences. When we introduce alien DNA using Pst I, it will cut the plasmid at its recognition site.
- If the alien DNA is inserted into the plasmid at the Pst I site, it will disrupt the function of the adjacent genes.

**Hint**: Understand how restriction enzymes work and what happens to the plasmid when foreign DNA is inserted.

3. **Insertional Inactivation**:
- The insertion of foreign DNA at the Pst I site will lead to the inactivation of the ampicillin resistance gene. This means that the transformants (the bacteria that take up the plasmid with the inserted DNA) will no longer be able to grow in the presence of ampicillin.

**Hint**: Recall the concept of insertional inactivation and how it affects gene function.

4. **Selection of Transformants**:
- Since the ampicillin resistance gene is inactivated, transformants will not survive on media containing ampicillin.
- However, the tetracycline resistance gene remains unaffected, allowing transformants to grow on tetracycline-containing media.

**Hint**: Consider how antibiotic resistance can be used to select for successful transformations.

5. **Conclusion**:
- Therefore, the transformants will grow on tetracycline but not on ampicillin. The correct answer to the question is that the transformants will grow on tetracycline.

**Hint**: Summarize the results of the transformation and the implications for growth on different media.

### Final Answer:
The transformants will grow on **tetracycline** (Option 2).