In genetic engineering, the antibiotics are used

Options

A. To keep the cultures free of infection
B. As selectable markers
C. To select healthy vectors
D. As sequences from where replication starts

Answer

**Step-by-Step Solution:**

1. **Understanding Genetic Engineering**: Genetic engineering involves manipulating an organism's DNA to achieve desired traits. This often includes the insertion of foreign DNA into a host organism.

2. **Role of Antibiotics**: In genetic engineering, antibiotics play a crucial role in ensuring that only the desired recombinant cells survive during the selection process.

3. **Selectable Markers**: Antibiotic resistance genes (like those for ampicillin or tetracycline) are often included in plasmid vectors. These genes serve as selectable markers.

4. **Transformation Process**: When plasmids containing the antibiotic resistance genes are introduced into host cells, not all cells will take up the plasmid. Only those that successfully incorporate the plasmid will express the antibiotic resistance.

5. **Selection of Recombinant Cells**: The host cells are then cultured in a medium that contains the corresponding antibiotic.
- Cells that have taken up the plasmid (recombinant cells) will survive because they can resist the antibiotic.
- Cells that have not taken up the plasmid (non-recombinant cells) will die in the presence of the antibiotic.

6. **Conclusion**: Therefore, antibiotics are used in genetic engineering primarily as selectable markers to differentiate between recombinant and non-recombinant cells.

**Final Answer**: In genetic engineering, antibiotics are used as selectable markers to identify and select recombinant cells that have successfully incorporated foreign DNA.

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