noun, plural: micromolecules
In biology, a micromolecule refers to a molecule of relatively small size and low molecular weight as opposed to a macromolecule, which is large and with greater molecular weight. While a macromolecule may be viewed as a biological polymer, which by definition is a substance made up of small monomeric units bonded together. In this sense, a micromolecule can be viewed as the monomer that comprises a polymer macromolecule. The four major biological molecules are nucleic acids, proteins, carbohydrates, and lipids. In this regard, a protein as a macromolecule is comprised of micromolecule monomers, amino acids linked together by peptide bonds.
Monomers are considered a micromolecule that can be linked together to form polymer (which is a macromolecule). Apart from the monomers (e.g. nucleotides, amino acids, monosaccharides, glycerol and fatty acids) that make up the four main biomolecules, inorganic compounds like water and minerals are also examples of micromolecules.
Word origin: micro- ("small") + molecule
- micromolecular (adjective, of, pertaining to, relating to, or characterizing a micromolecule)