Question

Assertion (A): DNA ligase plays an essential role in recombinant DNA technology.
Reason (R): The linking of antibiotic resistance genes with plasmid vectors became possible by enzyme DNA ligase.

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is not the correct explanation of A
• C. A is true but R is false
• D. Both A and R are false

Answer 1

The correct option is A Both A and R are true and R is the correct explanation of A

DNA ligase is also known as molecular glue. It plays an important role in the formation of recombinant DNA.

DNA molecules that have segments from two different biological sources/organisms are called recombinant DNA

The first recombinant DNA molecule was constructed by linking an antibiotic gene from Salmonella typhimurium with a plasmid of E.coli.

The plasmid of E.coli and the DNA containing antibiotic resistance gene were cut at specific locations with the help of restriction enzymes.

The antibiotic gene was then linked with plasmid DNA by using DNA ligase. It acts on cut DNA molecules and joins them by forming a phosphodiester bond.