In a way, sequencing DNA is very simple: There's a molecule, you look at it, and you write down what you find. You'd think it would be easy—and, for any one letter in the sequence, it is. The problem ...

DNA is the molecular basis of heredity, the inherited traits that pass between generations in a person's family tree. Embodied in the sequence of base pairs, DNA carries information between ...

This story is part of our series on viroids and virusoids, small infectious RNAs. The story is also the second installment in a series on hepatitis D virus, a virusoid-like pathogen that causes ...