Biology Reference
In-Depth Information
founders of genetics. In his opinion, living beings are totally con-
trolled by chromosomes. Although at that time DNA had not yet
been identified as the fundamental genetic material of heredity,
15
Delbrück had already suggested that hereditary material might be
composed of an aperiodic crystal in which the order of atoms deter-
mined the properties of the genes.
16
Schrödinger adopted this
hypothesis and suggested that chromosomes contain a virtual code
representing the organisms and the way in which they function: “
It
is these chromosomes,
(
...
)
that contain in some kind of code-script
the entire pattern of the individual's future development and of its
functioning in the mature state
” (WIL p. 21). In his view, someone
able to decipher this code would be able to foresee the organism con-
cerned and fully understand how it functions. Could these organisa-
tional properties of chromosomes arise therefore from the random
behaviour of the atoms that make them up, as happens in physical
systems? Schrödinger asserted that this was impossible because they
are not numerous enough, and to consolidate this assertion he relied
on a calculation he performed using data available at the time.
Obviously his reasoning may seem perfunctory today, but he had no
idea of the mechanisms of protein synthesis with which we are now
familiar. He estimated that a gene was composed of at most a mil-
lion atoms, which is very few compared with the size of physical sys-
tems, and would not allow the law of large numbers to eliminate
variance in the behaviour of these atoms. As Schrödinger put it,
“
That number is much too small
(
...
)
to entail an orderly and lawful
behaviour according to statistical physics
” (WIL p. 30.) Consequently,
in contrast to physical systems, order must already be present in bio-
logical systems at the molecular level itself and must be responsible
for the unique properties of living beings:
“… we are here obviously faced with events whose regular and law-
ful unfolding is guided by a 'mechanism' entirely different from the
'probability mechanism' of physics.
(
…
)
Whether we find it aston-
15
In general it was thought to involve proteins.
16
As we know, this hypothesis was confirmed subsequently with the discovery
of the genetic code carried by the structure of DNA.
