Biomolecule
An organic molecule produced by and essential to a living organism.
Unit
Dimensionless
In depth
The four principal classes are carbohydrates, proteins, lipids and nucleic acids. Three of these are polymers assembled from a small set of monomers by condensation, which is why life achieves vast structural diversity from remarkably few building blocks.
Examples in the real world
Glucose, haemoglobin, cholesterol and DNA; water and mineral ions are essential but not biomolecules.