The linking of antibiotic resistance gene with the plasmid vector became possible with

Options

A. Type II restriction endonucleases
B. Alkaline phosphatase (AP)
C. DNA ligase
D. Polynucleotide kinase

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the enzyme that enables the linking of an antibiotic resistance gene with a plasmid vector.

2. **Identifying the Role of Plasmids**: Plasmids are circular DNA molecules that can replicate independently of chromosomal DNA. They are often used as vectors to introduce foreign DNA into host cells.

3. **Recognizing the Importance of Enzymes**: In genetic engineering, specific enzymes are used to manipulate DNA. The question provides multiple options, and we need to identify which enzyme is responsible for linking the antibiotic resistance gene with the plasmid.

4. **Evaluating the Options**:
- **Type II Restriction Endonucleases**: These enzymes cut DNA at specific sequences. They are used to create fragments of DNA but do not join them.
- **Alkaline Phosphatase**: This enzyme modifies DNA by adding or removing phosphate groups but does not join DNA fragments.
- **DNA Ligase**: This enzyme is responsible for joining the ends of DNA fragments by forming phosphodiester bonds, making it crucial for linking genes to vectors.
- **Polynucleotide Kinase**: This enzyme adds phosphate groups to nucleotides but does not join DNA fragments.

5. **Conclusion**: The enzyme that facilitates the linking of an antibiotic resistance gene with a plasmid vector is **DNA ligase**. This enzyme acts on the cut ends of DNA and joins them, creating recombinant DNA.

6. **Final Answer**: The correct option is **DNA ligase**.

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