What are the monomers of such macromolecules

Although living cells are primarily made up of water, a number of other molecules are also abundant. Gigantic molecules, called macromolecules, populate a cell and provide it with important functions for life. For example, macromolecules provide structural support, a source of stored fuel, the ability to store and retrieve genetic information, and the ability to speed biochemical reactions. Four major types of macromolecules-proteins, carbohydrates, nucleic acids, and lipids-play these important roles in the life of a cell.

In terms of overall structure, all macromolecules except the lipids are considered polymers. A polymer is a chain of similar subunits, or monomers, that are linked together by covalent bonds. In proteins, the monomers are amino acids; in carbohydrates, the monomers are sugars; and in nucleic acids, the monomers are nucleotides. Lipids are a diverse group of molecules, which come in a variety of nonpolymeric forms.