From: Dace (email@example.com)
Date: Tue 22 Nov 2005 - 22:45:38 GMT
> At 21:50 16/11/2005, Dace wrote:
> >How do we get from molecular disorder to proteins
> >and organelles? How can we account for large-scale cellular order
> >to the model of contact mechanics? Where's the evidence that
> >order is built up, machine-like, from molecular components?
> >Secondly, it's not enough to simply link genotype to phenotype. Where is
> >the causal chain linking transcription of DNA to multicellular
> I'll try the first one of these: How do we get from molecular
> disorder to proteins and organelles?
> But first I need to know more about exactly what you mean by
> "molecular disorder". Proteins are manufactured in cells, and cells
> are highly ordered, so I'm not sure why you think that we have to be
> able to explain "molecular disorder -> protein" (that's Hoyle's
> fallacy again - I think your "cloud" analogy is another manifestation
> of that, anybody who's spent any time looking down a microscope would
> never think of using such an analogy). I'd like to rephrase the
> question as simply "how do we get proteins?" which is fairly
> straightforward to answer.
Nobody knows how we get proteins. It's called the multiple-minimum problem,
and it has yet to yield to a solution. But that's not the point. The point
is that from the perspective of physics, a cell is essentially a cloud in a
membrane. There seems to be no reason why a cell has any more order to it
than a cloud. Indeed, thermodynamics allows us to make predictions about
the behavior of a cloud, but these behaviors are obviously nowhere near as
detailed and precise as the behaviors of cells.
The large-scale patterns of activity in cells rest atop a foundation of pure
chaos. Reductionism drops down to the level of the macromolecule (genes and
proteins) and conveniently stops there without confronting the molecular
disorder that lies below.
> Actually, Ted, try this one:
> We know that related organisms have similar DNA sequences.
> We know that related organisms have similar developmental pathways.
> We know that mutational pressure on DNA is high.
> If developmental pathways are controlled by spooky fields and not
> DNA, then since mutational pressure is high, we would see a lot more
> divergence in DNA. Since we don't, it follows that developmental
> pathways are not controlled by spooky fields. QED.
As Elsasser hypothesizes, genes provide the "operative symbolism" that tells
the embryo what developmental pathway it should follow. The details of this
pathway are not contained in the symbol but in ancestral organisms.
Development is controlled through a combination of genes and fields. The
two forms of memory-- particulate and holistic-- are complementary.
> Try this one, Ted:
> A large object has a gravitational field. For instance, if the earth
> was split into two masses, each would still have a gravitational
> field (although the strength of gravity on the new smaller size
> planets would be different). Likewise, if a magnet is chopped in
> two, there are now two magnets. Therefore, for a phenomenon to
> qualify as a field, it must obey this kind of general non-destructability.
> So if there is some kind of field buzzing away around a fertilised
> egg, one would expect that field to be fundamentally equivalent if
> the egg was divided, ie. qua field, it ought to be able to produce 2
> So why is it then that this kind of experiment produces very variable
> results depending on the species and the time of the division? For
> instance, dividing a frog embryo at the 2-cell stage will get you 2
> little tadpoles instead of one. But try dividing a fly embryo - it
> just dies. Dividing a frog or sea-urchin embryo at the 4 and 8 cell
> stages will produce a variety of results - for instance at the 8 cell
> stage in the frog, you'll no longer get mini-tadpoles from your
> divisions, but partial tadpoles (eg ones that are all gut and no
> nervous system, and the converse). Sea-urchins are better at giving
> mini-embryos at later stages, but eventually they also start to give
> just partial embryos.
What this shows is that once an embryo has committed itself to a
developmental pathway, breaking it in two will result in two halves of an
organism. But prior to making that commitment, the embryo which is divided
will become two whole embryos. Why shouldn't this commitment occur at
different stages in different species?
> So this field is not much of a field really, is it? Or if it exists,
> whatever it is, it is clearly so different to the normal
> understanding of field as imported from physics, to invalidate the
Clearly not everything in biology is regulated by fields. Like Weiss says,
it's a mix of patterns (holistically determined) and matrices (mechanically
determined). Where it's holistic, it's just like any other field effect.
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