Who constructed the first recombinant DNA ?

Answer

**Step-by-Step Solution:**

1. **Identify the Scientists**: The first recombinant DNA was constructed by two scientists, Stanley Cohen and Herbert Boyer.

2. **Year of Construction**: This groundbreaking work was accomplished in the year 1972.

3. **Isolation of Gene**: The scientists isolated an antibiotic-resistant gene. This gene is significant because it allows organisms to survive in the presence of antibiotics.

4. **Use of Restriction Enzymes**: To isolate the antibiotic-resistant gene, they utilized restriction enzymes. These enzymes cut DNA at specific sequences, allowing for the isolation of the desired gene.

5. **Linking with Plasmid DNA**: The isolated antibiotic-resistant gene was then linked to plasmid DNA from *Salmonella typhimurium*. Plasmids are small circular DNA molecules that can replicate independently of chromosomal DNA.

6. **Function of the Plasmid**: The plasmid acts as a vector, which is a vehicle for transferring genetic material into another cell.

7. **Transformation into E. coli**: The recombinant plasmid containing the antibiotic resistance gene was then introduced into *Escherichia coli* (E. coli) cells. This process is known as transformation.

8. **Purpose of Transformation**: The purpose of transferring the plasmid into E. coli was to produce multiple copies of the antibiotic resistance gene, effectively creating a recombinant DNA molecule.

9. **Conclusion**: In summary, the first recombinant DNA was constructed by Stanley Cohen and Herbert Boyer in 1972 through the isolation of an antibiotic-resistant gene, its linkage to plasmid DNA, and the transformation of E. coli.

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