a basic unit of hereditary material; an ordered sequence
of nucleotide bases that encodes a product (this product
could be just RNA like rRNA or finally coding for a protein).
The gene includes, however, regions preceding and following
the coding region (5' UTR and 3' UTR) as well as (in eukaryotes)
intervening sequences (introns) between individual coding
There are many discussions between biologists to find
a comprehensive definition of a gene, which is not easy,
if possible at all.
See also cistron; locus; Mendel's first law.