Biology Reference
In-Depth Information
Structure
Life
=
Process
Mechanism
(Physical Laws)
Fig. 16.1
A triadic definition of life:
Structures, processes
, and
mechanisms
implementing the
laws of nature
are irreducible aspects of life. This diagram is consistent with Peirce's triadic
Thermodynamic and kinetic principles are essential to account for
processes
.
Ther-
modynamics
determines the direction of changes while
kinetics
determines the speed
of changes. The former is path-independent and the latter is path-dependent. Hence,
the former does not involve time while the latter does. The relation between kinetics
and thermodynamics may be somewhat akin to the relation between processes
(i.e., dissipative structures, or dissipatons) and structures (i.e., equilibrium structures
or equilibrons): Objects with equilibrium structures (e.g., oxygen and hydrogen
molecules) come first and then their interactions to form products, for example,
water, comes later. Generalizing, we may say
Process
>
Structures
(16.14)
where the expression, A
B, symbolizes the original relation in which “A embeds
B” or “A presupposes B.” In other words, the relation between structures and
processes is “ordinal” and “hierarchical” and not “compositional.”. That is, life,
for example, is not composed of
structures
and
processes
but rather life is selected
processes (thereby being associated with information) that embed or enclose
structures. This ideas may be diagrammatically represented as in Fig.
16.1
.
>
16.7 Active versus Passive Phase Transitions:
Is Life a Critical Phenomenon?
geometric scales - (1)
microscopic
(or molecular, 0.1-5 nm), (2)
mesoscopic
(or
cellular, 5-10
4
nm), and (3)
macroscopic
(or multicellular, greater than 10
5
nm).
The individual nodes in the gene, RNA, and protein spaces are on the microscopic
scale; their networks within individual spaces operate on the mesoscopic scale; and
finally the functions of multicellular systems such as tissues and organs (not shown)
operate on the macroscopic scale. Inseparable from the geometric (or spatial) scale
is the time (or temporal) scales over which living processes occur, ranging from
10
12
to ~10
9
s. These two distinct scales may be coupled in living systems through
Brownian (or thermal) motions of biopolymers that play fundamental roles in all
