What is the purpose of using plasmid DNA as a vector in genetic engineering?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → To deliver an alien piece of DNA into the host organism
A vector is a carrier. Just as the mosquito acts as an insect vector that carries the malarial parasite into the human body, a plasmid is used to carry an alien piece of DNA into the host organism. The plasmid can replicate on its own, so the DNA linked to it is copied in the host too.
Option (1) To deliver an alien piece of DNA into the host organism — Correct. Delivering alien DNA into the host is the purpose of using plasmid DNA as a vector.
Option (2) To cut the alien DNA at specific recognition sites — Incorrect. Cutting DNA at specific recognition sites is done by restriction enzymes, the molecular scissors.
Option (3) To join the cut ends of the alien DNA — Incorrect. Joining the cut ends of DNA is done by DNA ligase.
Option (4) To act as the host in which the recombinant protein is made — Incorrect. The host is a separate cell, such as E. coli, into which the plasmid is transferred. The plasmid is the carrier, not the host.
NCERT Extract:
Principles of Biotechnology – “… The cut piece of DNA was then linked with the plasmid DNA. These plasmid DNA act as vectors to transfer the piece of DNA attached to it. You probably know that mosquito acts as an insect vector to transfer the malarial parasite into human body. In the same way, a plasmid can be used as vector to deliver an alien piece of DNA into the host organism. The linking of antibiotic resistance gene with the plasmid vector became possible with the enzyme DNA ligase, which acts on cut DNA molecules and joins their ends.”