A macromolecule is a very large molecule made up of smaller repeating units called monomers, which are chemically bonded together to form polymers. These molecules have a high molecular mass and are essential components of living organisms as well as synthetic materials. In nature, common macromolecules include:

• Proteins, which are polymers of amino acids connected by peptide bonds.
• Nucleic acids (DNA and RNA), polymers of nucleotides joined by phosphodiester bonds.
• Polysaccharides like starch, cellulose, and chitin, which are polymers of monosaccharides linked by glycosidic bonds.
• Some lipids, which are organic nonpolar molecules with varied structures.

Macromolecules play crucial roles in biological functions and also exist as synthetic polymers like plastics and fibers. They are typically characterized by their large size and repeating structural units. Examples include biological macromolecules such as carbohydrates, lipids, proteins, and nucleic acids, and synthetic polymers like polyethylene and nylon.