The four types of macromolecules, or very large molecules, are nucleic acids, proteins, lipids and carbohydrates. All are biological polymers, except for lipids that, according to the University of New Mexico, are not considered to be made of monomers and thus are not polymers. Carbon is integral to all these types of molecules, with hydrogen, nitrogen, phosphorous and oxygen also playing a role in several of them.
The molecule of heredity, DNA, is classified as a nucleic acid as is RNA. These are complex polymers composed of monomers known as nucleotides. In eukaryotes, DNA is found within membrane-bound organelles known as nuclei. The molecules that carry the information encoded in DNA to the cellular machinery, RNA, are found throughout the cell and are created as they are needed.
Proteins are the main molecular machines of the cell and the structural support for animal cells. They are polymers composed of monomers known as amino acids. Each sequence of three nucleotides, known as a codon, represents one amino acid, which are assembled according to DNA instructions into proteins.
Carbohydrates are used as energy storage and structural support in plant cells. Large sugars, known as polysaccharides, are composed of smaller monosaccharides like glucose and fructose.
Lipids, which are critical to cell membranes and energy storage in animals, are composed of a glycerol or other group bonded to a number of fatty acid chains.