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

Options

A. Cohen and Boyer 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 statement provided in the options and determine which one is correct. Here’s a step-by-step breakdown:

### Step 1: Analyze the first statement
**Statement:** Cohen and Boyer were the first scientists to introduce a recombinant DNA in the year 1975.
- **Analysis:** This statement is incorrect. Cohen and Boyer actually introduced recombinant DNA technology in 1972, not 1975.

### Step 2: Analyze the second statement
**Statement:** They isolated the antibiotic-resistant gene by dissolving a piece of DNA from a plasmid.
- **Analysis:** This statement is also incorrect. The antibiotic-resistant gene was isolated using restriction endonucleases, which cut the DNA at specific sites, rather than by simply dissolving a piece of DNA.

### Step 3: Analyze the third statement
**Statement:** The antibiotic-resistant gene was linked to the plasmid vector using the enzyme DNA helicase.
- **Analysis:** This statement is incorrect. The correct enzyme used to link the antibiotic-resistant gene to the plasmid vector is DNA ligase, not DNA helicase.

### Step 4: Analyze the fourth statement
**Statement:** Antibiotic resistance gene was isolated from the native plasmid of Salmonella typhimurium.
- **Analysis:** This statement is correct. Cohen and Boyer did isolate the antibiotic-resistant gene from the plasmid of Salmonella typhimurium.

### Conclusion
After analyzing all the statements, the correct statement is:
**"Antibiotic resistance gene was isolated from the native plasmid of Salmonella typhimurium."**