Physical and functional unit of heredity which carries information from one generation to the next. In molecular terms, it is the entire DNA sequence – including exons, introns, and noncoding transcription-control regions – necessary for production of a functional protein or RNA.
The segment of DNA involved in producing a polypeptide chain. It includes regions preceding and following the coding region as well as intervening sequences (introns) between individual coding segments (exons). (Genes V, p.1242)