Bacteria Size

Dr Banwari Lal banwaril at teri.ernet.in
Sun Feb 23 00:49:31 EST 1997

> Mark Rothon <unbar at rothon.demon.co.uk> wrote in article
> <01bc18db$7ed4a1e0$4e93dec2 at rothon.demon.co.uk>...
> > I am an undergrad giving a talk on "why are bacteria small?".
> Can anyone
> > help by giving me any information or tell me where to look.
> > P.S. relative references would be useful, Many thanks.  :-)
> Bacteria are small because of the cell volume versus cell surface
> area
> (membrane area).  Eukaryotic cells have a number of membrane
> bound and
> other organelles to carry out respiration, energy transfer
> (electron
> cascade, proton motive force, ATP production), nutrient
> assimilation, waste
> disposal, etc., etc. etc.
> Prokaryotes (bacteria, archaea, etc.) do not have any organelles.
>  The
> outer membrane has to do it all.  Surface area can be increased
> by using
> rod, spiral, and helix geometries but it is still very limiting. 

I would look at this phenomenon in a slightly different
perspective. Most bacteria have a rapid rate of growth, provided
optimal growth conditions are maintained. It would make sense to
have a smaller genome size such that DNA replication is achieved 
at a faster rate. Therefore, one can speculate that the amount of
information stored should be economized, leading to lesser
complexity of cellular organization. I would also like to point out
here that, bacteria that have rapid multiplication rate have
circular genome. Which essentially helps DNA replication to be
fast. One might argue that, certain bacteria have linear genome,
Agrobacterium for instance. These bacteria take pretty long to grow
as well.

My guess is that, faster the multiplication rate, smaller the
genome size and complexity of cellular organization. One might
question, why do certain organasim multiply so frantically? My
guess is that we have not yet reached a stage from where we can
speculate anything. Someone out there on the NET might know better.
I shall look forward to hear about their opinion.
Hope this helps

| Banwari Lal, Ph.D.                      |~~~~~~~~~~~**~~~~~~~~~~|
| Microbial Biotechnology,                |~~~~~~~~~/::::\~~~~~~~~|
| TATA Energy Research Institute,         |~~~~~~~~~::::::~~~~~~~~|
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