Organic Compounds The Structure and Function of Macromolecules Biological Molecules The study of carbon compounds, organic chemistry, focuses on any compound with carbon (organic compounds) Proteins, DNA, carbohydrates, and other molecules that distinguish living matter from inorganic material are all composed of carbon atoms bonded to each other and to atoms of other elements Carbon Atoms Carbon is building block of molecules Carbon has 4 valence electrons Can form 4 covalent bonds Tetravalence by carbon makes large, complex molecules possible Carbon Skeletons Carbon chains form the skeletons of most organic molecules The skeletons may vary in length and may be straight, branched, or arranged in closed rings. The carbon skeletons may include double bonds.