172 NUCLEIC ACIDS, DECODING, ETC. 



one assumed that the "messenger" is produced in the form of 

 two, presumably antiparallel, strands as an image of the particular 

 segment of DNA, of which only one carries the "coded" infor- 

 mation, a sequence of salmon DNA which in a tract of 174 

 nucleotides contained only one adenylic acid looks most unreal 

 on many grounds. For instance, salmon DNA is of a quite 

 marked AT type (Table 39). 



You will notice that in salmon DNA almost every third 

 nucleotide has a good chance of being adenylic acid. How 

 probable is it then that this nucleotide occurs only once in such 

 a long stretch? Moreover, even a glance at the published "code" 

 will convince us that there can be very few proteins that would 

 demand a less implausible messenger. We are, hence, left with 

 the assumption that each double segment of DNA can specify, 

 via two RNA chains, two different amino acid sequences of 

 which only one is realized. But what does the other half of "mes- 

 senger" do and what is its fate? Surely, nobody would like to 

 put forward the inane slogan: One gene, two enzymes. 



Another explanation, but not a very good one, of these dif- 

 ficulties may be seen by some in the assumption that the code is 

 "degenerate", i.e., more than one triplet may specify one amino 

 acid. It should, however, be pointed out that if the "degeneracy" 

 took the form of having one triplet coding for a given amino acid 

 in one species, but another coding unit for the same amino acid 

 in another species, the proclaimed universality of the code would 

 vanish. And then there is, as always, still another possibility, 

 namely, that the whole thing is wrong. 



In any event, when I saw aU this I was very baffled. I concluded 

 that what I had tried to do will not be a shortcut towards a 

 solution of the problem of nucleotide sequence in RNA and 

 DNA. I went home and lost my faith. 



5 



Most scientists like to believe that we live in a cosmos, i.e., in 

 a universe having order, harmony, purpose. Many feel that in this 

 world all hangs together, though few will presume to explain how 



