The Natural Repertory of Prof. William Nelson

Jacobs, classified sugar of yeast nucleic acids as D-Ribose. This is linked
to the bases by a glycosidic bond. They termed these nucleosides.
Adenosine, guanosine, cytidine, and uridine, when esterified by
phosphates, became adenylic acid, guanylic acid, cytidylic acid, and
uridylic acid. It was Levene who later found that this sugar is RNA and
DNA was not a hexose, but a pentose.
Early determinations of the molecular weight of DNA gave values of the
order of 10 3. In 1938, Frederick Sanger proposed that its weight was 10 6 .
Levene also was able to confirm this new molecular weight in 1938.
In 1944, at the Rockefeller Institute Hospital, Oswald Avery came up
with the first strong evidence that DNA was really the key to transferring
genetic characteristics in microbes. Avery also proposed some of the DNA
enzymes, such as DNA depolymerase and deoxyribonuclease. These
enzymes were found to deactivate DNA, but were later key in the process
of unfolding and unwinding the DNA to set genetics in motion.
In 1945, DNA was found to have light absorption in the area of 260
nanometers, and to have some mitogenic-like production of UV. These
purines and pyrimidines were also found to have strong light
relationships; both absorption and production.
Erwin Chargaff in 1950 was able to show some of the strong light
spectrophoto reaction of the different components of DNA and DNA itself.
From this, the research finding adenine, guanine, cytosine, and thymine,
or A, G, C, and T, led to the discovery of the different Chargaff rules.
First, the total of purines and pyrimidines are quantitatively equi-
molecular; that is, A + G = T + C. Second, the molecular quantities of
adenine and thymine individually are equal: A = T. Third, the amounts of
guanine and cytosine are molecularly equivalent; G = C. A relation of the
preceding rules comes to the final rule in which A + C = G +T. Later, it
was found that uracil took the place of thymine in the RNA components
of the cell. These rules echo our quantum rules in many ways.
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