This is an amazing video animation from Nature Reviews Genetics!
This animation introduces the principles of RNAi involving small interfering RNAs (siRNAs) and microRNAs (miRNAs). It takes you on an audio-visual journey through the steps of gene expression and shows you an up-to-date view of how RNAi can silence specific mRNAs in the cytoplasm.
There is an accompanying slideshow which provides further information about RNAi and small RNAs.
High-resolution version can be found here: