Multicellular Systems - Molecular Theory of the Living Cell - page 541

In Sect. 2.4.1 , a bionetwork was defined as a network of nodes (n), such as
proteins, RNA, and DNA, connected by edges (e) according to some topology (T)
so as to accomplish a biological function (F), that is, F T(n,e). Statement 15.16

satisfies all the requirements of the definition of a bionetwork with the following
identifications:

¼

¼

1. F “evolutionarily selected functions of the organism”

¼ ...

2. T “the noncoding DNA regions determine the space- and time-dependent

control of their interactions ... ”
3. n ¼

“ ... coding regions of the DNA ... determine the intrinsic properties of

the nodes ... ”

4. e ¼ “the noncoding DNA regions determine ... the interactions among

the nodes”

Therefore, based on the empirical data shown in Fig. 15.15 and the bionetwork
theory described in Sect. 2.4.1 , it is possible to make the following equivalent or
related generalizations:
DNA of an organism encodes a bionetwork. (15.17)
DNA is a molecular representation of a bionetwork. (15.18)
Since DNA is a molecular representation of a bionetwork and since a bionetwork is a
graph-theoretical representation of an organism, DNA is a molecular representation of an
organism. (15.19)

Statement 15.19 may be referred to as the Bionetwork Theory of DNA (BTD),
and it is here suggested that BTD complements the Watson-Crick theory of DNA
(Watson and Crick 1953) which is mostly structural (or node-centered , in the
language of network sciences).
At least 50% of the non-protein-coding DNA of the human genome has been
found to code for RNA molecules that are not translated into proteins (Mattick
2004). Hence, Fig. 15.15 indicates that the level of RNA in cells most likely
increases with biological complexity, making RNA levels inside the cell (and
associated non-protein-coding DNA, or dr-genes; Sect. 11.2.4 ) a reliable index of
the complexity (the active kind; see Sect. 5.2.4 ) of the phenotype of multicellular
organism. Since maintaining complex structures of organisms would entail free
energy dissipation, the following generalization follows:

The more complex an organism is, the more energy the organism needs to survive. (15.20)
We will refer to Statement 15.20 as the Hypothesis of the Free Energy Requirement
for Active Complexity of Living Systems or more briefly as the Free Energy Require-
ment for Active Complexity (FERFAC) (for the definition of “active complexity”, see
Sect. 5.2.3 ). As discussed in connection with Fig. 15.13 , the allometric data on the
log-log relation between the bodyweight vs. the metabolic rate of various species, i.e.,
Eq. (15.14), strongly support the validity of the FERFAC hypothesis.