Biology Reference
In-Depth Information
Self-encapsulation will sharply differentiate the organization of the system
(the set of relations that constitute it as a distinct unity) from the environment,
where different interactions occur. In this way, a clearly distinct inner medium
is created: a space where not just concentrations, but even components will be
different from those of the “external” medium. However, the most important
issue is that the boundary is produced by the very organization of the system
(as it is an integral and integrated part of the metabolic network, not a mere
'wall' whose properties are externally defined). This entanglement, between the
physical border and the recursive process of production of components consti-
tuting the system as an autonomous unit, is basically the idea of an autopoietic
system (AS), as has been explained by Maturana and Varela (1973) 30 years ago.
However, the idea of autopoiesis has been formulated in a rather abstract
way. If we take into account the thermodynamic requirements, an AS should
also manage autonomously the flows of matter and energy necessary for its
maintenance. To be autonomous, a primitive SM system should be capable of
constraining the flows of energy (and matter) to ensure the TD realization of
the processes that constitute it as a system. In other words, the constructive
logic (the recursiveness of the relations among the components of the system)
should be entangled with the energetic logic (Moreno & Ruiz-Mirazo, 1999,
Ruiz Mirazo & Moreno, 2000, 2004). This implies that the membrane is not
only a physical border ensuring adequate concentrations, but also a key element
in the energetical maintenance of the system
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(Pereto, 2005). In any known
living system a phospholipid membrane and its molecular machines actively
control the flows of energy between the inside and the outside. The essence of
the energetic self-maintenance of the cells lies in the asymmetric disposition of
molecular machines on the cell membrane allowing efficient coupling between
primary energy sources and metabolic networks.
This thermodynamic view of autonomy goes far beyond the idea of logical
closure of autopoiesis. As a FFE organization, the constitutive processes, the
recursive network of production of components, of an autonomous system is
essentially entangled with a set of interactive processes. Thus, an autonomous
system is an agent, namely, a system that maintains its own identity by per-
forming functional processes on its environment (Moreno & Etxeberria, 2005,
Moreno & Barandiaran, 2005) (see Fig. 1).
These interactive processes are different from mere physico-chemical reac-
tions constantly taking place in both directions (and which, in fact, occur in all
kinds of systems, from the simplest to the most complex). As the interactive
processes are embedded in the self-constructing dynamics of the system, they
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Thus, such an interface needs to be a semi-permeable structure where coupling mechanisms (particularly
energetic transduction and active transport mechanisms), which are basic for the complete self-construction,
are anchored.
