Biology Reference
In-Depth Information
kinds of energies in physics - thermal, kinetic, potential, chemical, mechanical,
nuclear, Gibbs free energy, and Helmholtz free energy, etc. Little confusion arises in
distinguishing different kinds of energies in physics because of the availability of the
principles of classical mechanics, quantum mechanics, statistical mechanics, and
thermodynamics. To be able to differentiate among different kinds of information in
biology, computer science, and philosophy on the one hand and between
informations and energies on the other, it may be essential to utilize not only the
laws and principles of physics and chemistry but also those of
semiotics
, the study of
signs as developed by Peirce (1903) more than a century ago (see Sect.
6.2
).
5.2.3 Two Kinds of Complexities in Nature:
Passive and Active
We can recognize two kinds of “complexities” in nature -
active
and
passive
,in
analogy to
active
and
passive
transport. For example, snowflakes (Fig.
5.3
) exhibit
passive
complexity or complexification, while living cells (see the topic cover)
exhibit
active
complexity in addition to passive complexity. Unlike passive com-
plexity, active complexity is exhibited by living systems utilizing free energy, and
organisms with such a capability is thought to be more likely to survive
complex
environment than those with passive complexity only. According to the Law of
Requisite Variety (LRV) (Sect.
5.3.2
), no simple machines can perform complex
tasks. Applying LRV to cells, it can be inferred that
No simple cells can survive complex environment.
(5.10)
If this conjecture is true, it is not only to the advantage of cells (both as individuals
and as a lineage) but also essential for their survival to complexify (i.e., increase the
complexity of) their internal states.
One strategy cells appear to be using to complexify their internal states is to vary
the amino acid sequences of a given enzyme or of the subunits of an enzyme
complex such as ATP synthase and electron transfer complexes, each containing a
dozen or more subunits. This strategy of increasing the complexity of sequences
may be forced upon cells because they cannot increase, beyond some threshold
imposed by their physical dimensions, the variety of the spatial configurations of
the components within their small volumes. In other words, it is impossible to pack
in more than, say 10
9
, enzyme particles into the volume of the yeast cell, about
10
15
m
3
, but the yeast cells can increase the variety of their internal states by
increasing the variety of the amino acid sequences of their enzymes and enzyme
complexes almost without limit, as a simple combinatorial calculus would show.
For example, there would be at least 2
100
10
33
different kinds of 100-amino acid-
residue polypeptides if each position can be occupied by one of at least two
different amino acid residues. This line of thought led me to infer that there may
be a new principle operating in living systems, here referred to as the “Maximum
¼
