A bacterium having rDNA formed by using pBR322 and EcoRI restriction enzyme is resistant to :

Options

A. Penicillin and ampicillin
B. Ampicillin and tetracycline
C. Tetracycline only
D. Ampicilin only

Answer

To solve the question regarding the resistance of a bacterium having recombinant DNA (rDNA) formed using the pBR322 vector and the EcoRI restriction enzyme, we can follow these steps:

### Step 1: Understand the Components
- **pBR322**: This is a well-known plasmid used as a cloning vector in molecular biology. It contains genes that confer resistance to certain antibiotics.
- **EcoRI Restriction Enzyme**: This enzyme is used to cut DNA at specific sites, allowing for the insertion of foreign DNA into the plasmid.

### Step 2: Identify the Antibiotic Resistance Genes
- pBR322 contains two important antibiotic resistance genes:
- **Ampicillin Resistance Gene (bla)**: This gene allows bacteria to survive in the presence of ampicillin, an antibiotic.
- **Tetracycline Resistance Gene (tet)**: This gene provides resistance to tetracycline, another antibiotic.

### Step 3: Analyze the rDNA
- When rDNA is formed using pBR322 and EcoRI, the resulting recombinant plasmid will retain the antibiotic resistance genes present in pBR322.
- Therefore, the bacterium that contains this rDNA will be resistant to both ampicillin and tetracycline.

### Step 4: Determine the Correct Answer
- The question asks which antibiotics the bacterium is resistant to. Since the rDNA includes the genes for both ampicillin and tetracycline resistance, the correct answer is:
- **Ampicillin and Tetracycline**

### Final Answer:
The bacterium having rDNA formed by using pBR322 and EcoRI restriction enzyme is resistant to **Ampicillin and Tetracycline**.

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