Manoj Joshi, Social Zerology, Physics (atmmmj@vax.oxford.ac.uk) wrote:

: can anyone xplain to me what a gene is?

See Portin, 1993, "The Concept of the Gene: Short History and
Present Status", Quarterly Review of Biology 68(2): 173 - 223

The author argues that the concept of the gene has gone through
three periods, which he calls classical, neoclassical and
modern. The classical view is the gene is an indivisible unit
of genetic transmission. The neo-classical view is that the
gene (sometimes called a cistron) was responsible for producing
a single mRNA and hence a single protein. The modern view, in the
author's mind, incorporates split genes, alternate splicing, over-
lapping and nested genes as well as edited genes.

I've only skimmed the article (but let me add my highly biased
and tendentious opinions anyway8-) but I think the author is
confusing what a gene is with the form a gene takes. I subscribe
to a view that would be closest to the classical view -- a gene
is a heritable unit capable of being passed on intact for numer-
ous generations. The form that most genes take is a string of
nucleotides that code for a single protein. But, other elements
can be stably inherited and (IMHO) can be viewed as genes. For
an example, I would give cytoplasmic elements such as _Wolbachia_
bacteria, which is a cytoplasmically transmitted parasite that
alters sex-ratios in many insects. (It boosts the percentage of
females produced because it is not passed on through males).

The molecular biologists definition of a gene as a nucleotide
sequence is (IMHO) far too restrictive.

Chris Colby
email: colby@biology.edu