The document summarizes the key organic molecules found in living organisms: carbohydrates, lipids, proteins, and nucleic acids. It describes the carbon atom's ability to form chains and bonds that allow for a large diversity of molecules. The four biomolecule classes are composed of monomers that polymerize and have distinct structures and functions, such as carbohydrates providing energy, lipids storing energy and forming membranes, proteins enabling diverse cellular functions, and nucleic acids carrying genetic information and aiding protein production.