High Quality Content by WIKIPEDIA articles! RNA interference (RNAi) is a system within living cells that helps to control which genes are active and how active they are. Two types of small RNA molecules microRNA (miRNA) and small interfering RNA (siRNA) are central to RNA interference. RNAs are the direct products of genes, and these small RNAs can bind to specific other RNAs and either increase or decrease their activity, for example by preventing a messenger RNA from producing a protein. RNA interference has an important role in defending cells against parasitic genes viruses and transposons but also in directing development as well as gene expression in general.
