An important characteristic of nucleic acids is their nucleotide composition or, in other words,
composition and ratio of the consituent monomer units. In the late forties and early fifties,
when such research tools as paper chromatography and UV spectroscopy came into being,
many analyses of the composition of nucleic acids were carried out (Chargaff, Belozersky).
Their results provided a decisive argument for rejecting the older notions of nucleic acids as
polymers containing recurring tetranucleotide sequences (so-called tetranucleotide theory of
nucleic acid structure reigned supreme in the thirties and forties) and paved the way toward
modern concepts not only of the primary structure of DNA and RNA but also their
macromolecular structure and functions.