Biology Reference
In-Depth Information
regulator proteins could also leave the cell where they are synthe-
sised to enter other cells and exert their effect there. Coordinated
differentiation between several cell lines due to this intercellular
signalling could thus occur, explaining the global activity of all the
cells of an organism by networks of molecular interactions.
However, as with the case of morphogenesis by self-assembly,
for signalling and regulation of genetic expression to be effective it
is necessary for the underlying molecular interactions to obey the
rule of stereospecificity and for them not to generate any possibil-
ity of multiple combinations. If that were the case, several possible
responses would correspond to a given signal i.e. cell mechanisms
would no longer be deterministic. Molecular interactions must
therefore be as precise as cybernetic commands directing the liv-
ing being. As Monod says, it is “
…the huge network of cybernetic
interconnections which makes each organism an autonomous func-
tional unit...
” (CN p. 79).
For molecular biology, the organism is therefore still a deter-
ministic machine, though Descartes' old clock has been replaced by
a computer.
