Question

Silencing of specific mRNA in RNAi is by

• A. dsDNA
• B. SSRNA
• C. dsRNA
• D. ssDNA

Answer 1

The Correct Option is C

RNA interference (RNAi) is a mechanism that regulates gene expression by specifically targeting and degrading mRNA molecules. It is mediated by small RNA molecules, particularly small interfering RNAs (siRNAs) or short hairpin RNAs (shRNAs), which are derived from longer dsRNA molecules.

In the RNAi process, the dsRNA molecule is introduced into the cell, which is then processed by an enzyme called Dicer into siRNAs or shRNAs. These small RNA molecules bind to the target mRNA sequence, typically through complementary base pairing, forming a RNA-induced silencing complex (RISC).

The RISC complex guides the degradation or inhibition of the target mRNA, preventing its translation into protein. The silencing of specific mRNA through RNAi is a powerful tool in molecular biology research for studying gene function and has potential applications in therapeutics.

Answer 2

RNA interference (RNAi) is a powerful biological process in which RNA molecules inhibit gene expression, typically by causing the destruction of specific mRNA molecules. This "silencing" of mRNA prevents the production of the protein encoded by that mRNA.

The mechanism by which specific mRNA is silenced in RNAi is primarily through:

Binding to the mRNA and causing its degradation 

Here's a breakdown of the process:

1. Dicer Processing: Double-stranded RNA (dsRNA) is processed by an enzyme called Dicer into short interfering RNAs (siRNAs).
2. RISC Formation: One strand of the siRNA is loaded into a protein complex called the RNA-induced silencing complex (RISC).
3. Target Recognition: The siRNA guides the RISC to the target mRNA molecule that has a complementary sequence to the siRNA.
4. mRNA Cleavage: If the siRNA and mRNA have perfect or near-perfect complementarity, the RISC cleaves the mRNA, leading to its degradation and preventing translation.

Although translational repression can also occur, the primary mechanism for silencing specific mRNA in RNAi is the direct degradation of the mRNA molecule.