gene

A theoretical unit of heredity of living organisms which may take several values and (in principle) predetermines a precise trait of an organism's form (phenotype), such as hair color.

• Near-synonym: cistron (often synonymous)

A segment of DNA or RNA from a cell's or an organism's genome, that may take several forms and thus parameterizes a phenomenon, such as (often) the structure of a protein.

• Holonym: locus
• A change in a gene is reflected in the protein or RNA molecule that it codes for.