Small Interfering RNAs (siRNAs)

Definition

siRNAs are small pieces of double-stranded RNA with two nucleotides overhanging at each 3’ end. They interfere with the expression of specific genes with complementary nucleotide sequences by degrading mRNA after transcription, preventing translation.

Analogy

siRNAs act like scissors cutting up unwanted flyers before they can be distributed around town (the cell). The flyers represent mRNAs carrying messages for protein production - if they're cut up, their message can't be delivered!

Related terms

MicroRNA (miRNA): A type of non-coding RNA molecule that functions in RNA silencing and post-transcriptional regulation of gene expression.

Dicer Enzyme: An enzyme that cleaves long double-stranded RNA molecules into short fragments called siRNA or miRNA.

Post-Transcriptional Regulation: Control over gene expression after the mRNA has been produced during transcription but before it's translated into protein.