In RNAi (RNA interference) technology, which among the following is used in gene silencing?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → dsRNA
RNA interference (RNAi) is a method of cellular defence found in all eukaryotic organisms. A double stranded RNA (dsRNA) that is complementary to a particular mRNA binds to it and prevents its translation. The gene of that mRNA is thus silenced. In the protection of tobacco from a nematode, the host plant was made to produce sense and anti-sense RNA, which paired to form this dsRNA.
Option (1) dsRNA — Correct. dsRNA (double stranded RNA) is the molecule that binds to the complementary mRNA and silences it.
Option (2) dsDNA — Incorrect. dsDNA (double stranded DNA) is the usual form of the genetic material. It does not bind to mRNA, so it cannot block translation.
Option (3) ssRNA — Incorrect. ssRNA (single stranded RNA) is the form of an ordinary mRNA. RNAi starts only when two complementary RNA strands pair up into a double strand.
Option (4) ssDNA — Incorrect. ssDNA (single stranded DNA) is used as a probe in molecular diagnosis, not in gene silencing.
NCERT Extract:
Biotechnological Applications in Agriculture – “… RNAi takes place in all eukaryotic organisms as a method of cellular defense. This method involves silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA (silencing). The source of this complementary RNA could be from an infection by viruses having RNA genomes or mobile genetic elements (transposons) that replicate via an RNA intermediate.”