ABSTRACT
Why are things in biology the way they are? Such questions are not new to humankind. A century of work in biological chemistry now allows us, however, to expand their scope to the molecular level. We can therefore ask such questions about the chemical details of biomolecules ranging from genes to proteins to metabolism. Why are our genes built from four nucleotide letters (Benner, 2004)? Why are our proteins built from 20 directly encoded amino acids? Why is citric acid a key metabolite in the oxidative degradation of acetate? Why does terran life exploit water as its principal solvent?
