Which antibiotic resistance genes will you find in the modified vector pBR322?

Options

A. Ampicillin
B. Erthromycin
C. Tetracycline
D. Both ( 1) and (3)

Answer

To answer the question about which antibiotic resistance genes are found in the modified vector pBR322, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding pBR322**: pBR322 is a plasmid vector commonly used in molecular biology for cloning. It was one of the first vectors to be developed and is widely used due to its well-characterized features.

2. **Identifying Antibiotic Resistance Genes**: The modified pBR322 contains specific antibiotic resistance genes that allow for the selection of bacteria that have taken up the plasmid. The two primary antibiotic resistance genes present in pBR322 are:
- **Ampicillin Resistance Gene (bla)**: This gene provides resistance to the antibiotic ampicillin. Bacteria that successfully incorporate the pBR322 plasmid can survive in the presence of ampicillin.
- **Tetracycline Resistance Gene (tet)**: This gene provides resistance to the antibiotic tetracycline. Similar to the ampicillin resistance gene, it allows for the survival of bacteria in the presence of tetracycline.

3. **Evaluating the Options**: The question provides several options regarding the antibiotic resistance genes present in pBR322:
- **Option 1: Ampicillin** - Correct, as pBR322 contains the ampicillin resistance gene.
- **Option 2: Erythromycin** - Incorrect, as pBR322 does not contain the erythromycin resistance gene.
- **Option 3: Tetracycline** - Correct, as pBR322 contains the tetracycline resistance gene.
- **Option 4: Both 1st and 3rd** - Correct, as both ampicillin and tetracycline resistance genes are present in pBR322.

4. **Conclusion**: The correct answer to the question is **Option 4: Both 1st and 3rd**, as pBR322 contains genes for resistance to both ampicillin and tetracycline.