non-programmed cell death in eukaryotic plants & prokaryotes

Robert Goodman robgood at bestweb.net
Fri Jan 30 17:21:23 EST 2004


I want to teach my Plants & People students about a fundamental fact of
life: death.  A cell can reach a point of no return in sickness such that it
must die, death being a permanent condition.  In necrotic cell death in
eucaryotic animal cells, there's an unarguably irreversible step -- rupture
of
lysosomes.

However, most plant cells don't have an organelle called a lysosome.  One
source tells me they have organelles that do the same in necrosis, it's just
that they're not CALLED lysosomes.  That true?  If not, is necrosis in
plants akin to the death of procaryotes?

In procaryotes, I can only assume that at some point there's not enough
whatever to pay the "overhead" cost, and that it's like a business that
can't pay its operating expenses -- that it drains itself of the equivalent
of cash (free energy or possibly some other consumable).  And at some point
even an infusion of "cash" won't stop liquidation.  Am I right?  Bacteria
have a cell wall to prevent osmotic lysis, but they'll still lose viability,
and even
in the absence of a cell wall isosmotic medium doesn't make cells immortal.
Yes, you can maintain viability longer in stab or slant medium than in
liquid culture, but it's just a matter of time.

Yes, I know there are pathways leading to sporulation, and apoptosis is a
completely different pathway (or set of pathways) of death that's captured
so much research att'n, but I want to explain why all cells have to keep
paying
a maintenance cost or die.

Robert







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