How does RNAi “silence” a gene?

Verified step by step guidance

1. Understand that RNA interference (RNAi) is a biological process where RNA molecules inhibit gene expression by neutralizing targeted mRNA molecules.
2. Recognize that RNAi involves small RNA molecules, such as small interfering RNA (siRNA) or microRNA (miRNA), which are complementary to the mRNA of the gene to be silenced.
3. Learn that these small RNA molecules are incorporated into a protein complex called the RNA-induced silencing complex (RISC).
4. Know that the RISC uses the small RNA as a guide to bind to the complementary mRNA, leading to either cleavage and degradation of the mRNA or inhibition of its translation.
5. Conclude that by degrading or blocking the mRNA, RNAi effectively prevents the production of the protein encoded by the gene, thereby 'silencing' the gene.

Key Concepts

RNA Interference (RNAi) Mechanism

RNAi is a biological process where small RNA molecules inhibit gene expression by targeting specific mRNA molecules for degradation or translational repression, effectively reducing or silencing the production of the corresponding protein.

Role of Small Interfering RNA (siRNA) and MicroRNA (miRNA)

siRNAs and miRNAs are short RNA sequences that guide the RNA-induced silencing complex (RISC) to complementary mRNA targets, enabling the complex to cleave or block translation of the mRNA, thus preventing gene expression.

Gene Silencing via mRNA Degradation or Translational Repression

Once the RISC complex binds to the target mRNA, it either cleaves the mRNA, leading to its degradation, or blocks its translation, both of which prevent the mRNA from producing its protein, resulting in gene silencing.