As complex as the human body is, it is heavily dependent on just four atoms for its composition: carbon, hydrogen, nitrogen and oxygen. These atoms form structurally diverse groups of biologically important molecules, their structure always relating to their function in the same way that the cells and tissues of the body are adapted. Biomolecules commonly take part in relatively simple reactions which are subject to complex control to finely tune the essential processes that they mediate. Biomolecules are often large polymers made up from smaller molecular monomers and even though there are thousands of molecules in a cell there are relatively few major biomolecule classes. Fatty acids, monosaccharides, amino acids and nucleotides form di- and triglycerides, polysaccharides, proteins and nucleic acids respectively.
