ilya_prigogine_isabelle_stengers_alvin_tofflerbookfi-org

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inhibitions is an essential step in understanding the functional
logic of biological systems. This includes the triggering of syntheses
the moment they are needed and the blocking of those
chemical reactions whose unused products would accumulate
in the cell.
The basic mechanism through which molecular biology explains
the transmission and exploitation of genetic information
is itself a feedback loop, a "nonlinear" mechanism. Deoxyribonucleic
acid (DNA), which contains in sequential form all
the information required for the synthesis of the various basic
proteins needed in cell building and functioning, participates
in a sequence of reactions during which this information is translated
into the form of different protein sequences. Among the
proteins synthesized, some enzymes exert a feedback action
that activates or controls not only the different transformation
stages but also the autocatalytic mechanism of DNA replication,
by which genetic information is copied at the same rate
as the cells multiply.
Here we have a remarkable case of the convergence of two
sciences. The understanding attained here required complementary
developments in physics and biology, one toward the
complex and the other toward the elementary.
Indeed, from the point of view of physics, we now investigate
"complex" situations far removed from the ideal situations
that can be described in terms of equilibrium thermodynamics.
On the other hand, molecular biology succeeded in relating
living structures to a relatively small number of basic
biomolecules. Investigating the diversity of chemical mechanisms,
it discovered the intricacy of the metabolic reaction
chains, the subtle, complex logic of the control, inhibition, and
activation of the catalytic function of the enzymes associated
with the critical step of each of the metabolic chains. In this
way molecular biology provides the microscopic basis for the
instabilities that may occur in far-from-equilibrium conditions.
In a sense, living systems appear as a well-organized factory:
on the one hand, they are the site of multiple chemical
transformations; on the other, they present a remarkable "spacetime"
organization with highly nonuniform distribution of biochemical
material. We can now link function and structure.
Let us briefly consider two examples that have been studied
extensively in the past few years.