Molecular Weight of DNA
I have been curious about the atomic weight of DNA since
reading Isaac Asimov's book on the Chemicals of Life and he mentioned
how heavy a protein was in comparison to some inorganic compounds.
If I had known that Asimov's book was the root of your question, I would
have mentioned that proteins are huge compared to inorganic molecules;
as a matter of fact most organic molecules are much larger than most
inorganic molecules. An amino acid consists of an amine group and an
acid group with the amines fluctuating in size significantly, accounting
for the different amino acids codons (only 64 possible combinations).
DNA is just a library code to construct the different proteins in
particular orders of operation. Asimov was unaware of the significance
of operons and primers, so he did not gain a complete understand that
DNA is really smaller than the massive accumulation of the proteins a
DNA molecule can be coded to produce, and that RNA is really more the
chief "creator" of living things (arguably) on the molecular level. DNA
is principally a library that is "visited" when a code is needed. RNA
does the work. DNA is the "master" molecule only in the sense of a
library has the information needed. RNA reads the library and does all
the work to make the functional proteins (this statement is simplified;
actually there are a number (5+) of different RNAs working depending on
the organism and the function). Yes, of course DNA is active and not
interactive, I'm leaving that out!
You are going to have to forgive some of the omissions and
simplifications above, for this topic is complex. I have assumed that
you know some of the basic principles and can fill in the gaps.
Asimov was born too early, for if he was cognitively around today, I
would think he would be dancing in the streets with how this all works
(Human Genome Project, medical implications, etc.). Asimov, Bronowski,
and many other mathematicians and physics did understand decades before
the present that biology, and molecular biology in particular, will be
the culmination of all that science has learned during the last 300
(Copernicus) or 2500 (Greeks) years (depending on your position of the
History of Science). The "Century of Biology" has just begun.
Time magazine just recently offered the facts of how computer
programming code is too big and a great deal can be learned from DNA
code. Coding a human being is simpler than coding Word 2002! DNA
coding is 8-9 times simpler in comparison.
What you are reading and the questions you asked, speaks volumes for you
as an educator. It was fun thinking about all this.
La Grange, Illinois
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Update: June 2012