samodena at csemail.cropsci.ncsu.edu (S. A. Modena) writes:
[quotes, theology/ideology and some science deleted]
>Now, where do the molecularists stand in this? Certainly, the discipline is
>young...genetic engineering is a minimum of 10,000 years old...but molecular
>engineering is fairly recent. What does the "molbio.evolution" crowd
>have to offer? Certainly not "brain, mind, culture!" Mitochondrial Eve?
>No less controversial or suspect, right?
>Steve
>| At e-mail: nmodena at unity.ncsu.edu |
>|samodena at csemail.cropsci.ncsu.edu |
Well, a "crowd" is a crowd--bunch of uneducated "molecularists" who
don't even stand a comparison with enlightened and elite scientists
like Steve who even posess such wondrous sense of humor! "Mitochondrial
Eve"--how about that? Being acused of being "sexist", I wouldn't like
to aquire another "isms" saying that the last "outburst" of humor reeks
on profanity...
Anyway, let's "see" what molecular biology has to offer, without trying
to get into the old "classical" vs. "molecular" biology argument.
First of all, for an evolving system the question of effectiveness, i.e.
the ratio signal/noise can be taken as an informational criterium for
progress. Thereafter the "complexity" of regulation expressed in process
multiplexity per unit of consumed energy and levels of regulation can be
used as another criterium. Those criteria can be viewed in terms of sta-
tistical termodinamics also.
Anyway, viewing it by "levels", it can follow like this:
I. Chemical Evolution
1. Carbon Chain Polymers (n>6)
2. Evolution of Amino(-NH2) function in heterocyclic compounds.
3. First aminoacids and RNA
4. Macromolecular assemblies and first regulation aspects--"feed-
back". Pre-ribonucleoproteins and pre-enzymes.
II. Biochemical evolution
1. Multifunctional macromolecular assemblies.
2. Prion-like systems.
3. First DNA
4. Pre-membraneous organization. "Coacervation" and pre-protistae.
5. First Protistae(unicelulars)
III. Molecular-biological evolution(aspects)
1. Compartmentalization. Organelle specialization.
2. Gene "drifting" and "gene-block" assembly.
3. "Compression" of genetic material(overlaping, bidirectional,
multifunctional coding)
4. Multicelularity. Receptor/hormone type regulators and
regulatory networks.
5. "Gene burst"-evolution of multicistronic to unicistronic RNA's.
Interrupts, signal sequences and "junk". New structure-function
relationships in genetic material. Evolving of DNA-protein interac-
tions based on secondary and tertiary structure, "hot spots" of
interactions.
6. Multigene families and pseudogenes. High copy number protection.
Gene cascades and networks.
7. Cross-net and intranet regulations.
Now, this is a very rough and uncomplete outline of the "molecular"
aspects of evolution. I completely understand that there is no absolute
division between the "chemical" and "biochemical" or "biochemical" and
molecular-biological assembly level. But the evolving systems--the
first "cognate" molecule through the first macromolecular assembly to
cell structure and multicelularity are moving to higher "complexity"
not just thermodinamically, by chance, stochastically but by higher
hierarchy of self-organization. The system can "do" more "things" to
the environment, it has more "gates" which gives it lower entropy level
and higher information "flux".
I hope you also take in mind that the different outlined aspects of
"molecular evolution" are touching different system subsets and it
would be a work of a text in Molecular Biology to follow them all in
their development. Take for example the systems protecting the genetic
material--a subset for a whole chapter in a textbook. Neither the
bandwith, nor my awareness of the fact that there are very GOOD texts
in Molecular Biology permits me to be more explicit.
Thanks for the time you took to read this.
"There's no single truth."
arseny
