An enzyme used to replicate and produce multiple copies of r-DNA in the suitable host is

Options

A. DNA ligase
B. DNA polymerase
C. DNAse
D. Nuclease

Answer

To answer the question, "An enzyme used to replicate and produce multiple copies of r-DNA in a suitable host is," we need to identify the correct enzyme from the options provided.

### Step-by-Step Solution:

1. **Understanding r-DNA**:
- r-DNA stands for recombinant DNA, which is DNA that has been artificially created by combining DNA from different organisms.

2. **Identifying the Role of Enzymes**:
- In the process of creating r-DNA, various enzymes are involved. The key enzymes include DNA ligase, DNA polymerase, DNases, and nucleases.

3. **Evaluating the Enzymes**:
- **DNA Ligase**: This enzyme is crucial as it joins together DNA fragments, creating a stable and continuous DNA strand. It is essential for the final steps of DNA replication and for linking the inserted gene into the host DNA.
- **DNA Polymerase**: This enzyme synthesizes new DNA strands by adding nucleotides complementary to the template strand. It is important for DNA replication but not specifically for the integration of r-DNA.
- **DNases and Nucleases**: These enzymes degrade DNA and are not involved in the replication or production of r-DNA.

4. **Conclusion**:
- Among the enzymes mentioned, DNA ligase is the one that specifically helps in the replication and production of multiple copies of r-DNA by joining DNA fragments together. Therefore, the correct answer is **DNA ligase**.

### Final Answer:
The enzyme used to replicate and produce multiple copies of r-DNA in a suitable host is **DNA ligase**.

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