Biology Reference
In-Depth Information
Table 13.1 The logical and physical requirements for the mechanism of the origin of
molecular messages
as specified by H. Pattee (1969) are met by the
combination of the Anderson model of the origin of biological information (Fig.
13.2
) and the Princetonator (Fig.
13.3
)
Pattee's constraints on
mechanisms of the origin
of life (Pattee 1969)
Satisfied by
Anderson's model
The princetonator
1. Primeval ecosystem
The “RNA soup” on the
surface of the earth
subjected to thermal
cycling
2. Simple rules
Conformon
production and utilization
3. Switches
Frustrated regions of RNA harboring
conformons
(see Fig.
13.3
)
4. Open-ended
evolvability
Thermally accessible
conformations (called
virtual conformons
(Ji 1991, p. 136)) of RNA
fragments that can drive self-replication when reified to real conformons upon coupling
to exergonic chemical reactions, obeying the generalized Franck-Condon principle
(Ji 1991, pp. 50-56) (Sect.
2.2.3
). Due to thermal motions implicated, there is a finite
probability of errors occurring during the conformon-driven copolymerization process,
thus leading to mutations and open-ended evolution (Pattee 1995)
5. Stability
It is possible that n catalytically active molecular species (CAMS) must be colocalized in a
small spatial volume (to be called the catalytic site) to effectuate spontaneous
copolymerizations (see the Franck-Condon state defined on p. 433 in Ji 1974a and
Fig. 1 in Ji 1979). If the probability of such a colocalization is P and the average
probability of individual CAMS being located in the catalytic site is p, the following
relation holds: P
¼
p
n
. This simple power law indicates that the
stability
and the
probability of spontaneous formation
of the self-replicating systems (SRS) increases
and decreases, respectively, with increasing n. That is, the larger the value of n, the
smaller is the probability P and the greater would be the stability of SRS against its
accidental destruction by thermal motions
6. von Neumann limit
The
von Neumann limit
below which no SRSs can evolve may be identified with the
exponent n in the relation, P
¼
p
n
, because n is determined by the balance between two
opposing processes, namely, the spontaneous generation of SRSs (whose probability
decreases with n) and the stability of SRSs (whose probability increases with n). We
may refer to n as the
von Neumann exponent
