[extropy-chat] What is the smallest genome possible?
robert.bradbury at gmail.com
Sun Oct 15 18:27:55 UTC 2006
On 10/15/06, John K Clark <jonkc at att.net> wrote:
> It might be worthwhile to study it to find the bare minimum needed
> for life, perhaps they could try removing one of its 182 genes to see if
> they could get something even smaller.
Careful, careful, careful. As the article points out, it may be a bacteria
in the process of becoming an organelle! You could view a mitochondria as
being the smallest bacteria if you allow for bacteria to import proteins
essential for self-replication. The previous minimal genome size for
bacteria was thought to be in the 350-450 gene range so a 2-3x reduction is
not simply trimming around the edges.
The question is whether or not *all* the genes required for self-replication
are in those 182 genes? I would tend to doubt it. If you are importing
RNAs or proteins to accomplish complete replication then you are violating
the "rules". I suspect this could be extended if you are importing anything
other than simple molecules to produce a copy of yourself. (E.g. does the
bacteria do the synthesis of its cell membrane and/or wall or is relying on
the host to do the heavy lifting?)
This is going to cause rather loud discussions as to *what* precisely is a
bacteria? [And we thought the "what is a planet?" discussions were bad.] As
at least one virus has recently been found with a multi-thousand base genome
so I think the virus and bacteria definitions are starting to get very
Where is Humpty Dumpty when you need him?
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