A plasmid has accepted the gene of interest, such as gene coding for streptomycin. How can we make clones of this plasmid?

Options

A. Inserting it into a virus to generate multiple copies
B. Treating it with a restriction enzyme in order to cut the molecule into small pieces
C. Inserting it into a suitable bacterium in order to produce multiple copies
D. Running it on a gel electrophoresis in order to determine the size of the gene of interest

Answer

To clone a plasmid that has accepted the gene of interest (in this case, the gene coding for streptomycin), we can follow these steps:

### Step-by-Step Solution:

1. **Selection of the Plasmid**:
- Start with a plasmid that has been engineered to carry the gene of interest (the streptomycin gene). This plasmid should have a suitable origin of replication and a selectable marker (like antibiotic resistance).

**Hint**: Ensure that the plasmid has a selectable marker to identify successful clones.

2. **Preparation of Competent Cells**:
- Prepare competent bacterial cells (usually E. coli) that can take up the plasmid. This can be done through chemical methods (like calcium chloride treatment) or electroporation.

**Hint**: Competent cells are crucial for the uptake of plasmids.

3. **Transformation**:
- Introduce the plasmid into the competent bacterial cells through a process called transformation. This can be achieved by heat shock or electroporation, which facilitates the uptake of the plasmid by the bacteria.

**Hint**: Heat shock or electroporation helps the plasmid enter the bacterial cells.

4. **Recovery and Selection**:
- After transformation, allow the bacteria to recover in a suitable medium without antibiotics for a short period. Then, plate the bacteria on agar plates containing streptomycin or another antibiotic that the plasmid confers resistance to. Only the bacteria that have taken up the plasmid will survive.

**Hint**: Use antibiotic selection to isolate transformed bacteria.

5. **Colony Screening**:
- After incubation, colonies that grow on the selective medium can be screened to confirm the presence of the streptomycin gene. This can be done through PCR, restriction digestion, or sequencing.

**Hint**: Screening ensures that you have the correct clones with the gene of interest.

6. **Amplification**:
- Once confirmed, the selected colonies can be cultured in larger volumes to produce more plasmid DNA. This can be done using plasmid isolation kits or standard alkaline lysis methods.

**Hint**: Culturing selected colonies allows for the amplification of the plasmid.

7. **Analysis of Clones**:
- Finally, analyze the isolated plasmid DNA to confirm that it contains the streptomycin gene and that it is intact.

**Hint**: Verification of the plasmid ensures that the cloning process was successful.

### Summary:
To clone a plasmid containing the streptomycin gene, you need to prepare competent bacterial cells, transform them with the plasmid, select for successful transformants, and then amplify and verify the plasmid.