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Here's what I found out about all this stuff:

First we have the fertilized egg. This egg consists of an outer mem-
brane, the cytosol and the nucleus. While the outer membrane separa-
tes the cell from the environment, the cytosol is a solution of pro-
teins, electrolytes and carbonhydrates - some of these "ingredients"
are called organelles (e.g. mitochondria, Golgi apparatus, lysosomes
or centrioles, etc.). Every nucleus is covered in a porous membrane,
surrounded by the RNA (a messenger to the DNA). The inner of the nu-
cleus consists of chromatin material and the chromosomes (containing
DNA double helices).

Each DNA molecule consists of complementary base pairs - adenine (A)
and thymine (T), guanine (G) and cytosine (C). Only the both comple-
mentary bases can connect to each other via hydrogen bonds - two for
the A-T pair, three for the C-G pair.

This far for the "assembly" of an egg (or any other cell).

<http://www.unomaha.edu/~swick/2740mitosis.html> the process of cell
"cleavage" (mitosis).

How RNA works:

<http://staff.jccc.net/pdecell/proteinsynthesis/transcript.html#overview>

How DNA replication works:

<http://staff.jccc.net/pdecell/proteinsynthesis/dnareprokary.html>
<http://staff.jccc.net/pdecell/proteinsynthesis/dnarepli.html>

About genes:

<http://staff.jccc.net/pdecell/expression/control.html>

Here you can see that the double helix - which looks quite symmetric
from the outside - is anything else than symmetric seen from inside.

Some other interesting websites about the topics:

<http://staff.jccc.net/pdecell/cells/basiccell.html>


George Hammond wrote:

>bv_schornak wrote:
>
>>George Hammond wrote:
>>
>>>stew dean wrote:      
>>>
>>>>>The point is the brain is a 3-axis mirror symmetirc construct
>>>>>which begins at the 8 cell stage in embryology (1st 3 cleavages).
>>>>>          
>>>>>
>>>>Let's review that again - the brain is roughly symmetrical along one
>>>>axis, as is  the rest of the body. You have DNA to thank for this.
>>>>        
>>>>
>>>[Hammond]
>>>Really?  I'm only claiming the Left-right symmetry of the
>>>body comes from the first cleavage of the Egg (a fact proved
>>>by Roux, Conklin and others).  You just stated that it comes
>>>      
>>>
>>>from DNA.... what makes you think that?
>>    
>>
>>You've already forgotten that we get two complete (but half
>>sized) organisms, if we separate both cells after the first
>>cleavage? And four quarter sized organisms after the second
>>cleavage? George, George...
>>
>>Where else than in the DNA should the information about the
>>final organism sit?    
>>
>
>[Hammond]
>Well, I happen to agree with you, but I don't see any way to prove it.
>Early on I had the idea that the DNA DOUBLE HELIX was actually
>a gometrical map of the human body.
>

Not for real. It holds the information, but the "genetic map" is not
a map of the body. It provides instructions how to assemble a cell -
nothing else. Which kind of cell is produced depends on the RNA (and
the organelles).

>In fact the longitudinal
>lay out of the HOX Genes in a DNA strand ARE isomorphic to the
>longitudinal axis of the animal body.
>

Are you _really_ shure about that? No one knows, which of the groups
represent which part of an organism - DNA mapping is in its earliest
stage. Even if our entire DNA is mapped meanwhile, we don't know too
much about which gene is responsible for which cells.

>  So then I had the idea that
>the RH half of the DNA helix caused the RH side of the body, and
>LH half of the helix caused the LH side of the body.  But I've never
>seen any evidence for that.  Still, I suspect there is a connection!
>

There is none. The DNA cannot work if it is "one half", it needs the
complementary part to work properly. And if the both halves are com-
pleted, they are identical copies of each other.

>Maybe in very primitive animals it was... but just like "totipotency"
>in Eggs, the thing finally developed so either half of the DNA
>string can build a cell.... 
>

Yes, they do. But not as a "half DNA" - the mechanism of replication
includes splitting up _and_ copying the missing half (by attaching a
matching base to form the new base pair - C-G or A-T).

>fact of the matter is I don't know that much
>about genetics.... but I'll tell you what... if you ever nail down
>this principle that the "Double Helix" is a "homunculous of the body"
>be sure to put in for your Nobel Prize.
>

This isn't a visual "assembly instruction". The RAM in your computer
represents the structure of the internal organisation of its "cells"
much better than the DNA represents the structure of the final orga-
nism. DNA has more of a complex database, where data might be stored
anywhere in the available storage "room".

>   Frankly I think the guy who suggested this is actually on to something,
>because I've suspected it for years.... problem I think is, that it is
>buried
>way back in Evolution somewhere with very primitive cells and animals
>when such a thing actually DID exist... in fact there are probably still
>signs of it in the modern animal.  Most likely, the "cleavage of the double
>helix" has something to do with the "cleavage of the egg".... what
>do they call it..... "mitosis"?
>

Yep - mitosis is the process from triggering the chromosomes to copy
themselves until the final cell division.

>   The way I understand mitosis is that the DNA "chromosome" actually
>doubles into "two double helices" and then separates so one double
>helix goes to each daughter cell during cleavage.  I'll bet "originally"
>the double helix itself separated and one helix each went to each daughter
>cell,
>and then inside the daughter cells they doubled again.  This probably proved
>too risky, so it finally developed a method of doubling first, and then
>separating into the doughter cells..... or something like that.
>

<http://staff.jccc.net/pdecell/proteinsynthesis/dnarepli.html> shows
three possible ways to replicate a double helix - conservative, dis-
persive and semi-conservative. In general, the semi-conservative way
is used in real cells.

>   The other thing to investigate is whether it is only ONE side of the
>double
>helix which is used to produce cells, or whether BOTH SIDES are actually
>read by RNA?  I don't in fact know the answer to this basic question.
>I posted this to bionet.biphysics, maybe someone there can tell us
>something?
>

RNA is a messenger between the outside of the nucleus and the DNA in
the nucleus (which resides in the chromosomes).

These are two brief description how DNA parts are copied to RNA:

<http://www.accessexcellence.org/RC/VL/GG/protein_synthesis.html>
<http://www.accessexcellence.org/RC/VL/GG/rna_synth.html>

I think it is sufficient for the moment. To get deeper into this, it
would take a lot of time. My "special interests" are programming and
electronics, not biology. Would be interesting, but I don't have the
time to learn all this stuff...


Greetings from Augsburg

Bernhard Schornak