Question

Which of the following was a major contribution of Stanley Cohen in creating the first recombinant DNA molecule?

• A. Developing a method of removing the plasmids from one cell and then reinserting them in other cells
• B. Discovery of reverse transcriptase
• C. Combining a gene from a plant with a plasmid of Escherichia coli
• D. All of these

Answer 1

The correct option is A Developing a method of removing the plasmids from one cell and then reinserting them in other cells

Recombinant DNA refers to DNA that has been formed artificially by combining DNA segments from one or more than one organism into another host DNA by using various enzymes.

Stanley Cohen and Herbert Boyer generated the first recombinant DNA molecule by combining a gene from a bacterium of Salmonella typhimurium with a plasmid of Escherichia coli.

Boyer studied many restriction enzymes related to E.coli. These enzymes were specific in their cutting locations. They cut DNA.

Cohen worked on plasmids, isolated them from one bacterium and then reinserted them into another cell. Plasmids are self-replicating circular DNA found in certain bacteria. They are used as vectors to carry the gene of interest in genetic engineering.

Work of both these scientists helped to specifically isolate, insert segments of DNA in host cells and use them as factories to produce various products like plant proteins.

Working independently, Baltimore and Temin discovered reverse transcriptase, an enzyme that synthesizes DNA from RNA.