From a Biological site: All living things are made up of four classes of biological molecules: carbohydrates, lipids, proteins, and nucleic acids Is that right? Is everything in the body made from simple ingredients? The nucleic acids are macromolecules made from Please Register or Log in to view the hidden image! carbohydrates,(same as Fructose, but a little more complicated) Please Register or Log in to view the hidden image! and nucleotides, which are purines , and phosphates. Can anyone see any molecule which the body uses, which could not be made from these bases. Obviously we need metals as salts from eating them and some vitamins from the same source. Do we make all the purines?