Bacteria Size

Hiranya Roychowdhury hroychow at NMSU.EDU
Sun Feb 23 13:08:12 EST 1997

At 05:49 AM 2/23/97 -0000, Dr Banwari Lal wrote:
>> 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.  :-)

>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.                      |~~~~~~~~~~~**~~~~~~~~~~|


This, in itself, is probably a classical 'chicken and the egg' pradigm. While it may be argued that the smaller size of the genome makes sense for rapid multiplication, whether the short generation times for prokaryotes is the result of lower comlexity of the genome is also worth considering. Some eukaryotic cells also have rather remarkably short cell cycle times despite the enormity of their genomes. I think it is the survival advantage, imparted by short generation time due to the small genome size, that determined the size of these organisms in the first place.

Well, my Sunday afternoon's two-cents worth of time kill...

Dr. Hiranya Sankar Roychowdhury
Plant Genetic Engineering Lab.
New Mexico State University
Las Cruces, NM 88003
Ph. (505) 646-5785
hroychow at nmsu.edu

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