Gene Structure and Architecture - Any DNA sequence which codes for a functional protein does qualify as a gene provided it contains some extra regions with specific function.

For genes which encode proteins, a distinction can be made between information translated into polypeptide sequence and untranslated information.

In bacteria, the translated region (open reading frame or coding region) is equivalent to the gene and genes are usually separated by short internal non coding regions.

The genes at the extreme ends of the operon are also flanked by a non coding region which may be termed as the 5 untranslated region (UTR) or leader sequence and the 3 UTR or trailer sequence.