A single unit in a polymer; used for both a single nucleotide in DNA or a single amino acid in a protein.

An amino acid when referred to as part of a polypeptide chain.

General term for the unit of a polymer. That portion of a sugar, amino acid, or nucleotide that is retained as part of the polymer chain during the process of polymerization.

A chemical unit, such as an amino acid, of a large molecule.

a nucleic acid for DNA or an amino acid for a protein

a single molecular unit within a polymer

Part of a chemical structure that originates from a building block. In the case of peptides and proteins, this refers to amino acids.

an amino acid in/from a protein (described as a component of the polypeptide chain).