Biology Reference
In-Depth Information
Table 14.11 The key principles, laws, and concepts underlying the six steps of the MTLC-based
model of biological evolution shown in Fig.
14.7
Steps
Principles, laws, concepts
0
Conformons (Chap.
8
)
1
Protein folding controlled by both Gibbs free energy and genetic information,
2
Universal principle of thermal excitations (Sect.
12.12
)
3
Generalized Franck-Condon principle, also called the principle of slow and fast
4
5
Functions first and sequences second postulate (Statement 14.38)
What distinguishes the MTLC-based model of biological evolution
schematically presented in Fig.
14.7
and those proposed by Huynen and van
Nimwegen (1998) and by Zeldovich et al. (2007a, b, 2008) is that all of the key
steps implicated in the model are associated with at least one clearly formulated
physical principle, law, or concept. These are listed in Table
14.11
without any
detailed explanations, since they have already been explained in the indicated
chapter and sections of this topic.
According to the MTLC-based model of evolution depicted in Fig.
14.7
, the
evolution of organisms depends on five critical entities operating properly, namely,
sequences (or genes, RNAs, proteins) (designated as node A), ground-state
conformations of critical proteins (node B), functionally significant excited states
of critical proteins (node C), the critically important exergonic chemical reactions
(e.g., respiration, active transport, muscle contraction) (node D), and critically
important IDSs (node E). Unlike the Zeldovich-Shakhnovich model where the
probability that an organism is alive, P
alive
, is directly related to the probability
that the
weakest-link protein
(i.e., the protein whose malfunctioning leads to death)
be in its native (i.e., functional) state, P
nat
(i)
, as indicated by Eq. 14.33, which leads
to the rate equation for organismal death, Eq. 14.34, the MTLC-based model of
evolution suggests an alternative equation, Eq. 14.39, that can be obtained by
replacing P
nat
(i)
in Eq. 14.33 with P(E):
P
alive
1
P(E)
(14.40)
where
symbolizes proportionality, and P(E) is the probability that the critical
IDS (i.e., node E in Fig.
14.7
) under a given environmental condition is in its
“native state” or “functional state.” The rate of organismal death predicted by the
MTLC-based model of evolution (BME), then, can be obtained by inserting P(E) to
Eq. 14.34, leading to Eq. 14.40:
1
d
¼
d
0
1
½
P
ð
E
Þ
(14.41)
