Protein
We've all heard of protein, but it's so much more than the main ingredient in the Atkins diet. Proteins are highly complex molecules made of strings of amino acids. Proteins more or less run living cells; they perform the biochemical tasks that allow molecules to be broken down or built up, they form structural supports, and they do many other amazing and essential things. The exact sequence of amino acids in every protein corresponds to a gene in the DNA; in fact, the main thing DNA is for is to store the information telling how proteins should be built. So, the study of protein sequences and the study of DNA sequences go hand in hand.