Thomas D. Schneider 1
version = 5.74 of ccmm.tex 1999 December 9
Version 5.67 was submitted 1990 December 5
Schneider, T. D. (1991).
Theory of molecular machines. I. Channel capacity of molecular
machines.
J. Theor. Biol. 148, 83-123.
http://www.lecb.ncifcrf.gov/~toms/paper/ccmm
Like macroscopic machines, molecular-sized machines are limited by
their material components, their
design, and their use of power.
One of these limits
is the maximum number of states that a machine can choose from.
The logarithm to the base 2 of the
number of states is defined to be
the number of bits of information that the machine
could ``gain'' during its operation.
The maximum possible information gain is a function of
the energy that a molecular machine
dissipates into the surrounding medium (Py),
the thermal noise energy
which disturbs the machine (Ny)and the number of independently moving parts involved in the operation
(dspace):
bits per operation.
This ``machine capacity'' is closely related to
Shannon's channel capacity for
communications systems.
An important theorem that Shannon proved for communication channels also applies to molecular machines. With regard to molecular machines, the theorem states that if the amount of information which a machine gains is less than or equal to Cy, then the error rate (frequency of failure) can be made arbitrarily small by using a sufficiently complex coding of the molecular machine's operation. Thus, the capacity of a molecular machine is sharply limited by the dissipation and the thermal noise, but the machine failure rate can be reduced to whatever low level may be required for the organism to survive.
If you want to understand life, don't think about vibrant, throbbing gels and oozes, think about information technology.
-- Richard Dawkins [Dawkins, 1986]