A foreign gene is inserted in pBR322 using the restriction endonuclease EcoRl . Which of these is true about the E. coli having this pBR322 ?

Options

A. It will be resistant to both antibiotic ampicillin as well as antibiotic tetracycline
B. It will be resistant to antibiotic ampicillin but not resistant to antibiotic tetracycline
C. It will be resistant to antibiotic tetracycline but not resistant to antibiotic ampicillin
D. It will be neither be resistance to antibiotic tetracycline nor to antibiotic ampicillin

Answer

To solve the question regarding the consequences of inserting a foreign gene into the pBR322 plasmid using the restriction endonuclease EcoRI, 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 is widely used as a cloning vector in molecular biology.

**Hint**: Remember that pBR322 is a common vector used for cloning, and it has specific genes that confer resistance to antibiotics.

2. **Role of EcoRI**:
- EcoRI is a restriction endonuclease that cuts DNA at specific sequences. When a foreign gene is inserted into pBR322 using EcoRI, it typically disrupts the existing genes for antibiotic resistance.

**Hint**: Think about how restriction enzymes work; they cut DNA at specific sites, which can disrupt existing genes.

3. **Insertion of the Foreign Gene**:
- When the foreign gene is inserted into the pBR322 plasmid, it interrupts the genes responsible for resistance to ampicillin and tetracycline. This means that the plasmid can no longer confer resistance to these antibiotics.

**Hint**: Consider what happens when a gene is disrupted; it often leads to the loss of function of that gene.

4. **Consequences for E. coli**:
- The E. coli cells that take up this modified pBR322 will not be able to resist the effects of ampicillin and tetracycline because the genes for resistance have been silenced due to the insertion of the foreign gene.

**Hint**: Reflect on the implications of losing antibiotic resistance; the bacteria will be sensitive to those antibiotics.

5. **Evaluating the Options**:
- Given the above information, we can evaluate the options:
- **Option 1**: Resistant to both ampicillin and tetracycline. (Incorrect)
- **Option 2**: Resistant to ampicillin but not resistant to tetracycline. (Incorrect)
- **Option 3**: Neither resistant to ampicillin nor tetracycline. (Correct)

**Hint**: Compare each option with the consequences of the gene insertion to determine which is true.

### Final Answer:
The correct statement about the E. coli having the modified pBR322 is that it is **neither resistant to ampicillin nor tetracycline**.