gene

1. (genetics) 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.Examples: "Near-synonym: cistron (often synonymous)"; "The US supreme court has ruled unanimously that natural human genes cannot be patented, a decision that scientists and civil rights campaigners said removed a major barrier to patient care and medical innovation."

2. (molecular biology) 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.Examples: "Holonym: locus"; "A change in a gene is reflected in the protein or RNA molecule that it codes for."; "A length of DNA is divided into segments called chromosomes and shorter individual units called genes."