Which one of the following organisms has been disarmed and used to deliver desirable genes into animal cells?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Retroviruses
Some pathogens have learnt how to deliver their genes into the cells of a host. Scientists make use of this. They disarm the pathogen, which means that its disease-causing genes are removed, and use it as a cloning vector to carry a gene of interest. The Ti plasmid of Agrobacterium has been disarmed for plants. For animal cells, retroviruses have been disarmed.
(1) Retroviruses — Correct. They have been disarmed and are now used to deliver desirable genes into animal cells.
(2) Cyanobacteria — Incorrect. These are photosynthetic bacteria. Many of them fix atmospheric nitrogen and are used as biofertilisers. They are not used as vectors for animal cells.
(3) Yeast — Incorrect. It is a harmless fungus used for making bread and alcohol. It is not a pathogen that has been disarmed.
(4) Baculoviruses — Incorrect. NCERT names a baculovirus, Nucleopolyhedrovirus, as a biocontrol agent against insects. It does not name it as a vector for animal cells.
NCERT Extract:
Cloning Vectors – “… The tumor inducing (Ti) plasmid of Agrobacterium tumifaciens has now been modified into a cloning vector which is no more pathogenic to the plants but is still able to use the mechanisms to deliver genes of our interest into a variety of plants. Similarly, retroviruses have also been disarmed and are now used to deliver desirable genes into animal cells.”