> I am in the middle of much work and cannot dedicate the time to learn and
> discuss the interesting issue that we are discussing. I did look at the
> you mentioned and I found the following:
> "Life," in this contest is defined as follows: "--- any system which can
> independently do all four of the following:"
> 1. "Delineate itself from its environment through the production and
> maintenance of a membrane equivalent, most probably a rudimentary or
> quasi-active-transport membrane necessary for selective absorption of
> nutrients, excretion of wastes, and overcoming osmotic and toxic gradients,
> 2. Capture, transduce, store, and call up energy for utilization (work),
> 3. Actively replicate, not just passively polymerize or crystallize, and
> 4. Write, store, and pass along seemingly conceptual information that
> orders' for what is to be manufactured in the future, and to actually bring
> to pass those processes and "factory products" out of linguistic-like coded
> (codon) messages ('recipes') into physical biochemical, biological, and
> thermodynamic reality."
> Are the protocells of Fox alive according to the above definition?
Dr. Aristotel Pappelis and Dr. Donald Ugent seem to believe so. Item 1 is
simply a description of cellularity, tem 2 of metabolism and item 3 of
reproduction, which are three of the four criteria Fox used (and which his
protocells demonstrate). Fox's fourth criterion was response to external
stimuli. The organizers of the webpage Pappelis and Ugent were writing about
didn't use that criterion. Instead they describe what sounds like a
combination of anabolism (that part of metabolism responsible for synthesis)
and transcription/translation. Fox's protocells can synthesize both peptides
and polynucleotides, but whether they fit the description of item 4 depends
upon how you interpret it. Not even Fox has claimed that his protocells had
a proto-transcription/translation system, but they didn't need one either.
His protocells can absorb proteinoids directly from the environment; they
don't need to make their own. It is therefore possible that item 4 may for
some part describe more advanced features that did not appear until later in
the history of the origin of life. Their absence would not disqualify a
protocell from being alive if the protocell didn't need them to live.
Kevin L. O'Brien