With all the posts to catch up on, I seem to be making Terry work
overtime moderating today!
> In other words, is the globin example an extremely idealized case,
>or is the functional distribution of genes within a genome rather
>commonplace for the most part?<
Genes with related functions do not necessarily occur close together.
The position and function of genes are generally best known for
bacteria, and apart from a couple of conserved sequences, there seems
to be near-total shuffling of the genome. However, especially in
eukaryotes, the three-dimensional configuration of the genome is
poorly known, and it is possible that some genes with related
functions are positioned near each other due to configuration of the
chromosomes rather than due to gene sequence..
Globins have the added factor of being derived from duplication of an
ancestral gene. Some mechanisms of duplication generate adjacent
copies, and so proximity of genes with related function could be
historical rather than functional in some cases. On the other hand,
I know of no reason why gene duplication would produce a sequence of
genes on the chromosome that match their sequence of function durng
development, as is the case for a set of human globin genes.
Dr. David Campbell
Old Seashells
University of Alabama
Biodiversity & Systematics
Dept. Biological Sciences
Box 870345
Tuscaloosa, AL 35487 USA
bivalve@mail.davidson.alumlink.com
That is Uncle Joe, taken in the masonic regalia of a Grand Exalted
Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at
Droitgate Spa
This archive was generated by hypermail 2b29 : Thu Jul 04 2002 - 18:46:20 EDT