During the construction of the first rDNA, plasmid of which bacterium is used

Options

A. Haemophilus influenzae
B. Escherichia coli
C. Bacillus amyloliquifaciens
D. Salmonella typhimurium

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which bacterium's plasmid was used during the construction of the first recombinant DNA (rDNA).

2. **Definition of rDNA**: Recombinant DNA (rDNA) is a form of DNA that is created by combining DNA from different sources. This technology allows for the manipulation of genetic material.

3. **Historical Context**: The term "plasmid" was first introduced by Joshua Lederberg in 1952. Plasmids are small, circular DNA molecules found in bacteria that can replicate independently of chromosomal DNA.

4. **Role of Plasmids in rDNA**: Plasmids can carry genes that confer certain traits, such as antibiotic resistance. These plasmids can be used as vectors to introduce foreign DNA into a host organism.

5. **Identifying the Plasmid Used**: The first rDNA technology utilized the plasmid from the bacterium *Salmonella typhimurium*. This bacterium's plasmid was instrumental in the generation of the first rDNA molecule.

6. **Conclusion**: Therefore, the correct answer to the question is that the plasmid of *Salmonella typhimurium* was used during the construction of the first rDNA.

**Final Answer**: The plasmid of *Salmonella typhimurium* was used during the construction of the first recombinant DNA (rDNA).

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