With the help of DNA ligase donor DNA fragment is joined. It is called

Options

A. Molecular cloning
B. Tissue culture
C. Protoplasmic fusion
D. Splicing

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the process in which a donor DNA fragment is joined using the enzyme DNA ligase.

2. **Identifying Key Terms**: The key terms in the question are "DNA ligase" and "donor DNA fragment." DNA ligase is an enzyme that facilitates the joining of DNA strands together.

3. **Exploring Options**: The options provided are:
- Molecular cloning
- Tissue culture
- Protoplasmic fusion
- Splicing

4. **Analyzing Each Option**:
- **Molecular Cloning**: This is a method in molecular biology that involves joining recombinant DNA molecules and replicating them within a host organism. DNA ligase is crucial in this process as it joins the DNA fragments.
- **Tissue Culture**: This refers to the growth of tissues or cells in an artificial medium, which does not involve DNA ligase or the joining of DNA fragments.
- **Protoplasmic Fusion**: This is the fusion of two different types of protoplasts (cells without a cell wall), which is unrelated to DNA ligase.
- **Splicing**: This is a post-transcriptional modification where introns are removed from RNA, allowing for the coding of multiple proteins from a single gene. It does not involve DNA ligase.

5. **Conclusion**: Based on the analysis, the correct answer is **Molecular Cloning**, as it directly involves the joining of DNA fragments using DNA ligase.

**Final Answer**: Molecular Cloning

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