Select the correct statement from the following with reference to the work by Cohen and Boyer

Options

A. Cohen and Boryen were the first scientists to introduce a recombinant DNA in the year 1975
B. They isolated the antibiotic resistance gene by dissolving a piece of DNA from a plasmid.
C. The antibiotic resistance gene was linked to the plamid vector using the enzyme DNA helicase .
D. The antibiotic resistance gene was isolated from the native plasmid of Salmonella typhimurim.

Answer

To solve the question regarding the work of Cohen and Boyer, we need to analyze each of the provided statements and determine which one is correct based on historical facts about their contributions to recombinant DNA technology.

### Step-by-Step Solution:

1. **Understanding the Context**: Cohen and Boyer are known for their pioneering work in recombinant DNA technology, which began in the early 1970s. They successfully created the first recombinant DNA molecule.

2. **Evaluating Statement 1**: "Cohen and Boyer were the first scientists to introduce a recombinant DNA in the year 1975."
- **Analysis**: This statement is incorrect. The first recombinant DNA molecule was created in 1972, not 1975.

3. **Evaluating Statement 2**: "They isolated the antibiotic resistant gene by dissolving a piece of DNA from a plasmid."
- **Analysis**: This statement is misleading. The process involved cutting DNA, not dissolving it. They used restriction enzymes to cut the DNA.

4. **Evaluating Statement 3**: "The antibiotic resistant gene was linked to the plasmid vector using the enzyme DNA helicase."
- **Analysis**: This statement is incorrect. DNA helicase is involved in unwinding DNA strands, not in linking DNA fragments. The correct enzyme used for joining DNA fragments is DNA ligase.

5. **Evaluating Statement 4**: "The antibiotic resistant gene was isolated from the native plasmid of Salmonella typhimurium."
- **Analysis**: This statement is correct. They did isolate the antibiotic resistance gene from the plasmid of Salmonella typhimurium.

6. **Conclusion**: Based on the evaluations, the correct statement regarding the work of Cohen and Boyer is the fourth one: "The antibiotic resistant gene was isolated from the native plasmid of Salmonella typhimurium."