Answer :
Final answer:
The correct molecule involved in RNA interference (RNAi) to block gene expression is small interfering RNAs (siRNAs). siRNAs bind to mRNA, preventing its translation into proteins. Thus option (A) siRNAs is the correct option.
Explanation:
Gene expression can be blocked by a process called RNA interference (RNAi). Among the molecules involved in this process, small interfering RNAs (siRNAs) play a critical role. siRNAs interfere with gene expression by binding to messenger RNA (mRNA), preventing translation and protein synthesis. Therefore, the correct answer to the student's question is A) siRNAs. The RNAi mechanism includes several steps involving siRNAs or microRNAs (miRNAs). These molecules are cleaved by endonucleases like DICER into short strands, which are then incorporated into an RNA-induced silencing complex (RISC). The siRNA-RISC complex subsequently binds to complementary mRNA, leading to its cleavage and preventing the synthesis of the associated protein, thereby silencing the gene.
