Page 108 - Visions of the Future Chemistry and Life Science

The secret of Nature’s microscopic patterns 97

embodies these principles and has provided structures which were func-
tional and have stood the test of time. Furthermore, the Greeks were aware
of some fundamental patterns in nature. Their architects recognised the
intrinsic aesthetic value of the ‘golden ratio’ (1:1.618) which is derived
from adjacent numbers in the Fibonacci series. The same mathematical
series governs many space-filling operations in nature, seen most obvi-
ously in the arrangement of scales in a pine cone or of seeds on a sunflower
head.
The DNA (our blueprint) gives rise to proteins (commonly our compo-
nents) by converting the genetic code into a sequence of linked amino acid
units. The proteins roll up in a specific (self-assembling) way governed by
the interactions of the side chains. Some, by a long history of chance and
evolutionary selection, behave as efficient catalysts (enzymes) to bring
about the formation of other types of molecule from the same simple com-
ponents. Others break apart molecules releasing energy to power these pro-
cesses. The self-assembly of biological molecules and synthetic analogues
has received some attention from biochemists, but exactly how does an
organism progress from such a molecular cocktail to something with a
spinal column, a stem or a complex silica shell? What is the workforce that
operates to achieve construction from our genetic blueprint?

6.1.2 The inertia of natural patterns
In his inspiring work On growth and form, D’Arcy Thompson saw that the
production of many relatively small scale biological structures such as
radiolarian skeletons and the spiral shells of many marine organisms
resulted from packing phenomena (as in pine cones or sunflowers) upon
surfaces or in three dimensions. Today his work is perhaps seen as being
overly directed to the description of nature by ‘natural’ mathematical
rules, very much in the Greek tradition. However, the nub of his argument
still has great merit; rules do apply in development and, as expounded by
Kauffman, they are those of biophysics and chemistry acting at the inter-
faces of components derived from the molecular soup within cells. Further,
it is the interaction between cells so constructed and constrained that gives
rise to the varied shapes of multicellular organisms, including ourselves.
Nonetheless, it is at the scale of single-celled organisms that the mecha-
nisms of self-assembly are most apparent and close observation of the often
spectacular architecture displayed at this level, should give clues to the
nature of these mechanisms. These interactions, as noted by Thompson,