What is the main purpose of using modified retroviruses in genetic engineering?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → To deliver desirable genes into animal cells
A vector is a carrier that takes a gene into a host cell. Some pathogens already know how to put their genes into cells: Agrobacterium does it in plants and retroviruses do it in animals, where they turn normal cells cancerous. Scientists have disarmed retroviruses so that they no longer cause disease and now use them to carry desirable genes into animal cells.
Option (1) To induce plant growth — Incorrect. Retroviruses are animal viruses. In plants the vector used is the Ti plasmid of Agrobacterium, and its job is gene transfer, not growth.
Option (2) To deliver desirable genes into animal cells — Correct. Disarmed retroviruses are used as vectors to deliver desirable genes into animal cells.
Option (3) To transform bacteria into viruses — Incorrect. Vectors do not change one kind of organism into another. They only carry a gene into a host cell.
Option (4) To create new antibiotics — Incorrect. Antibiotics are made by microbes such as Penicillium. Retroviruses are not used to make antibiotics.
NCERT Extract:
Cloning Vectors – “… Similarly, retroviruses in animals have the ability to transform normal cells into cancerous cells. A better understanding of the art of delivering genes by pathogens in their eukaryotic hosts has generated knowledge to transform these tools of pathogens into useful vectors for delivering genes of interest to humans. … Similarly, retroviruses have also been disarmed and are now used to deliver desirable genes into animal cells.”