The human genome encodes snippets of RNAs ranging from 21–23 nucleotides in length, called microRNAs (miRNAs). Rather than code for proteins, miRNAs instead sabotage the translation of mRNAs. miRNAs are first generated as longer, hairpin-like precursors in the nucleus. In the cytoplasm, a collection of enzymes strips down the hairpins into their tiny and unwound final structure. miRNA-bound mRN...