Biology Reference
In-Depth Information
Table 6.3 (continued)
———————————————————————————————————————
d
Space- and time-specific intracellular gradients of ions, biochemicals, and mechanical stresses
(e.g., of the cytoskeletal system) that serve as the immediate driving forces for all cell functions on
the microscopic level (see Chap.
9
)
e
Also called “conformational” interactions which involve neither breaking nor forming covalent
bonds and depend only on the rotation around, or bending of, covalent bonds. Non-covalent
interactions implicate smaller energy changes (typically around 1-3 kcal/mol) than covalent
interactions which entail energy changes in the range of 30-100 kcal/mol
f
Molecular interactions that involve changes in covalent bonds, that is, changes in valence
electronic configurations around nuclei of atoms within a molecule
g
This row is added to the original table published in (Ji 1997a,b). The
third articulation
(Ji 2005a)
is a generalization and an extension of
second articulation
. Intercellular communication through
chemical concentration gradients is well established in microbiology in the phenomenon of
quorum sensing
(Sect.
15.7
) (Waters et al. 2008; Stock et al. 2000), whereby bacteria express a
set of genes only if there are enough of them around so that they can combine and coordinate their
efforts to accomplish a common task which is beyond the capability of individual bacteria. This
phenomenon can be viewed as a form of
reasoning
and
computing
on the molecular level and the
cell therefore can be viewed as
the smallest computational unit
(Ji 1999a)
,
which may be referred
to as
the computon,
a new term used here for the first time
mandated by Shannon's channel capacity equation (see Sect.
4.8
). For artificial
communication systems, the requisite energy is provided
externally
(e.g., a power
station); for natural communication systems such as cells, the needed energy is
generated from chemical reactions occurring
internally
utilizing chemicals provided
by their environment. This difference in the sources of energy may have profound role
in determining the global differences between artificial and living systems (e.g., macro
vs micro sizes of system components).
3. The complementarity between determinism and non-determinism (6.12)
The process of communication can be viewed as a complementary union of
determinism
and
nondeterminism.
The deterministic aspect of communication
reflects both the energy requirement (e.g., PSO, MERIT) and the syntactic rules
(e.g., grammar) inherent in the language employed in communication, and the
nondeterministic aspect (e.g., the principle of the arbitrariness of signs [PAS], the
principle of rule-governed creativity [RGC], both described in Sect.
6.1.4
) reflects
the freedom of choice available to the sender of a message. Shannon's formula,
indicates that, when there is no choice (i.e., no uncertainty), there is no information
(Pattee 2008, p. 119), since “no choice” means “no selection,” which in turn
signifies “no reduction” in uncertainty.
To summarize, cell and human languages are
symmetric
with respect to at least
five principles. Thus, to borrow the idioms of the group theory in mathematics, it
may be stated that cell and human languages are the members of a
symmetry group
that has five “symmetry operators,” here identified with (1) PSO, (2) MERIT, (3)
CDN, (4) PAS, and (5) RGC, and hence may be designated as SG(5), where S and G
stand for symmetry and group, respectively, and the Arabic numeral indicates the
number of the principles that remain unchanged (or invariant, or symmetric) when
