The Rna Interference ( Rnai ) Pathway

2224 Words Nov 28th, 2014 9 Pages
The RNA interference (RNAi) pathway is an important biological system that is utilised by many organisms as a method of regulating gene expression. But what exactly is RNAi? And what is the importance of its use and application in biology?
RNAi is a cellular process that actively silences specific genes. This method of post-translational gene regulation has been observed in many organisms including plants, fungi, some bacteria and animals. RNAi inhibits protein synthesis of the target transcript by the use of small RNA molecules that target messenger RNA (mRNA) within the cytoplasm following transcription by an RNA polymerase. RNAi occurs during translation of the mRNA by inhibiting the action of Ribosomes that catalyse this process within the cell. RNAi relies on a pathway involving a group of specialised proteins, which act in processing larger RNAs into small interfering RNA molecules (siRNA) and short hairpin RNAs (shRNA), which are involved in the molecular process of inducing gene silencing.
Longer double stranded RNAs (dsRNA) are transcribes within the cell itself endogenously and are processed by the Ribonuclease protein Dicer, which cleaves the dsRNA into smaller fragments of siRNA approximately 20 base pairs in length (Bernstein, et al. 2001). Experimentally, siRNA can also be introduced exogenously in order to manipulate gene expression. Cleavage into siRNA allows activation and binding to the RNA Induced Silencing Complex (RISC), where siRNAs bind to the…
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