Re: Epigenetic Determination of Antibiotic Resistance in Bacteria

On Jan 24, 11:11 am, CNCa...@xxxxxxx wrote:
On Jan 23, 10:01 pm, The Pooflinger <thepooflin...@xxxxxxxxx> wrote:

On Jan 23, 7:19 pm, CNCa...@xxxxxxx wrote:

I am not aware of any
experiment
or any observation, on any gene or group of genes, being responsible
for
any supramolecular structure (flagellum, Golgi Apparatus, chromosomes,
centrioles, vacuoles etc.). Are you?

Clarification needed here... are you saying you've never seen anything
describing genes responsible for said structures? Or am I misreading
something here?

Let me make clear my point. We know for a fact that genes are
responsible
for protein biosynthesis according to the genetic code in which a
triplet codes for an amino acid. This is the only thing we know with
certainty
about genes. But cells are not bags filled with proteins. Cells
contain various organelles
and other supramolecular structures composed of various proteins,
carbohydrates, lipids etc. arranged in strictly determined patterns in
a process
that requires investment of considerable amounts of information.

By and large, that "information" resides in relatively small stretches
of amino acid sequence that affect interaction with other copies of
the same protein or with other proteins. Still, it is *sequence*
information encoded in the DNA.

The genetic informationfor the biosynthesis of proteins contained in
genes and in DNA
in general is qualitatively inappropriate. No one has proven or  even
tried to
speculate how genetic information could provide instructions to
proteins,
carbohydrates, lipids and other components to form supracellular
structures.


As a matter of fact, there has been extensive research on the assembly
mechanisms of homo- and hetero-meric enzymes and other structures.
Much of this research has been genetic dissection of the specific
sequences (specific aa's encoded by DNA) involved in generating the
observed multimeric assembly. Certain sequence changes can eliminate
the capacity to form multimers. Others can, in some cases, increase
the likelihood. And there are all possible intermediate states
between proteins that have no affinity to each other to those that
bind very tightly to each other (e.g., in bacterial flagella the amino
end of FliG and the carboxy end of FliF interact very tightly; the
carboxy end of FliG, however, must interact more weakly with the MotA
protein -- if it bound it too tightly and not transiently, then there
would be no rotation).

Where that information comes from is a still unresolved problem of the
modern biology.

Nothing is ever completely resolved and there could be surprises, but
self-assembly of protein complexes is not a complete mystery -- we
know quite a bit about it. And, largely, the information that directs
assembly is sequence information in the proteins. And thus,
ultimately, sequence information in the DNA encoding proteins.

Evidence from studies of Sonneborn et al in 60-70s of the 20th century
have shown that
some form of nongenetic, epigenetic information is responsible for the
"cortical inheritance".
in unicellular ciliates such as Paramecium.

And that is an example of a kind of chaperone-like assembly, where a
new system forms from information in a pre-existing subunit. Prions
have a similar effect.

It is known, e.g. that
centrioles
provide epigenetic information for their replication and centrosomes
provide information for
organization of the cytoskeleton.

In *some* organisms.

More complex forms of epigenetic
information are used in multicellulars.

Evidence? Examples? You are the one making this claim. Present some
evidence to support it. Not assertions (largely false) that genes do
not affect morphology, but evidence that non-genetic information
does. Do you believe that assembly is due to information provided by
the "assembly fairies" in each cell? Where is it that you think the
'information' for assembly exists?

N.C.

.

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