  This paper presents, for the first time, four diversity types of protein
amino acids. The first type includes two amino acids (G, P), both without
standard hydrocarbon side chains; the second one four amino acids, as two pairs
[(A, L), (V, I)], all with standard hydrocarbon side chains; the third type
comprises the six amino acids, as three pairs [(F, Y), (H, W), (C, M)], two
aromatic, two hetero aromatic and two "hetero" non-aromatic); finally, the
fourth type consists of eight amino acids, as four pairs [(S, T), (D, E), (N,
Q), (K, R)], all with a functional group which also exists in amino acid
functional group (wholly presented: H2N-\.CH-COOH; separately: OH, COOH, CONH2,
NH2). The insight into existence of four types of diversity was possible only
after an insight into the existence of some very new arithmetical regularities,
which were so far unknown. Also, as for showing these four types was necessary
to reveal the relationships between several key harmonic structures of the
genetic code (which we presented in our previous works), this paper is also a
review article of the author's researches of the genetic code. By this, the
review itself shows that the said harmonic structures are connected through the
same (or near the same) chemically determined amino acid pairs, 10 pairs out of
the 190 possible.
