section_path: Chemical basis/Macromolecules
section_name: Macromolecules
paragraph_text: Macromolecules
  
  Macromolecules are large molecules made up of smaller subunits or monomers. Monomers include sugars, amino acids, and nucleotides. Carbohydrates include monomers and polymers of sugars. Lipids are the only class of macromolecules that are not made up of polymers. They include steroids, phospholipids, and fats, largely nonpolar and hydrophobic (water-repelling) substances. Proteins are the most diverse of the macromolecules. They include enzymes, transport proteins, large signaling molecules, antibodies, and structural proteins. The basic unit (or monomer) of a protein is an amino acid. Twenty amino acids are used in proteins. Nucleic acids are polymers of nucleotides. Their function is to store, transmit, and express hereditary information.