sugar, biochemistry of. Sugar, to a chemist, refers not to a single compound, but to any one of a class of molecules called the saccharides. Many saccharides, though not all, taste sweet. Sucrose, common table sugar, is a crystalline white solid at room temperature. Its chemical formula is C12H22O11 and its formal chemical name is α-D-glucopyranosyl-β-D-fructofuranoside. Sucrose is a disaccharide, comprising two simple sugars, glucose and fructose, linked through an oxygen atom. See glucose and fructose. Glucose has five carbon atoms and a single oxygen atom arranged in a six-membered ring that is folded up like a lounge chair. Fructose is based on a not-quite planar five-membered ring, made up of four carbons and a single oxygen atom.