reproduction of living systems, since without them the peptides thus formed
would have been exhausted and/or eventually hydrolized.
The clarification of these issues is a necessary condition for
overcoming the second “white spot” in biology. Decisive roles in that can be
played by quantum chemistry and molecular biology.
What has been said up to this point shows that the argument about what
has arisen earlier — proteins or nucleic acids — is not meaningless. It is
difficult to conceive a scenario in which they have simultaneously come on the
scene at the time of a siutable structural organization, and as a result from
their interactions life has emerged. Such an approach makes the evolutionary
process meaningless. It is even more difficult to accept the dominant pioneer
role of nucleic acids that is imposed by some authors. Eigen (1973) is quite
right stating that there can be no “function”, if there is no “information”. But this
“information” is not necessarily due to be in the form of nucleic acid
macromolecules (Fox, 1975). As Bernal (1969) has very well put it “the picture
of a solitary DNA-molecule on the Ocean shore giving rise to the entire
ensuing life is less plausible than the one of Adam and Eve in the garden of
Eden”.
Is the Genetic Code Universal and Invariable?
The idea implying the existence of a genetic code has cropped up in 1953
immediately after the discovery of the spatial structure of DNA and its
determination as the sole bearer of genetic information. The necessity of
elucidating the question how the hereditary information incorporated in it is
transferred to the protein molecules enhanced interest in that field.
According to present day views the genetic code is the order of the
arrangement of the bases (respectively the nucleotides) in nucleic acids (see
Fig. 2–37 A, B) which determines the amino acid sequences in protein
molecules. Since amino acids building proteins amount to 20 and the bases
to 4, the first two variants of singlet and diplet codes were unacceptable. The
well-known physicist and mathematician G. Gamov (1954) has forwarded the
initial pattern of the triplet model of the genetic code in which one amino acid
is coded for by three nucleotides called triplets or codons. In that case
(4³=64) the number of the participating amino acids is exceeded. That is why
it was accepted that to each amino acid correspond several triplets which is
known as degeneration of code and some of the triplets not encoding
amino acids were named non-sense or stop-codons.
The discovery of the genetic code is a great achievement in biology
finalized by the composition of the code dictionary in 1965 (Table 2). A great
number of scientists have devoted their efforts to the study of the genetic
code such as the world famous F. Crick, A. Kornberg, S. Brenner, M.
Nirenberg, G. Khorana, S. Ochoa, etc. Its practical decipherment was begun
by the classic work of Nirenberg and Matthaei (1961) when an artificial
protein (polyphenylalanine) consisting of only one amino acid (phenylalanine)