Introduction

Like a cookbook recipe, DNA (Deoxyribonucleic acid) provides the essential instructions to make proteins. Since DNA never leaves the nucleolus of the cell, the information from DNA gets copied into mRNA (messenger Ribonucleic acid) molecules by a process called transcription. In eukaryotes, the mRNA molecule leaves the nucleus and goes to an organelle known as the ribosome. Here, the mRNA is translated into polypeptides (polymer of amino acids). However, if the polypeptides are arranged abnormally, drugs are commonly used to block the production of these polypeptides in order to prevent diseases.  In 1998, scientists discovered a new process of silencing of specific gene expression triggered by double-stranded RNA (dsRNA), which is much more effective than the blocking of the production of proteins. In 2006, this exciting discovery earned scientists Andrew Fire and Craig Mello a Nobel Prize in Physiology or Medicine. RNA silencing processes are present in almost all eukaryotes. Depending on the organism and the source of the dsRNA trigger, this process controls transcriptional and/or post-transcription gene silencing.