WHY DOES DNA CODE CONSIST OF 4 LETTERS

The answer to this question is not yet known. There are two ways to ex press information, i. e., to reduce the number of letters in alphabet (n), which simplifies the decoding machine, but leads to longer inform ational sequences, or to increase n, which shortens sequences, but com plicates the informational machine. The compromise between these two p ossibilities would be to obtain the minimum of one of summary informat ional component's parameters. The summary component Is the sum of corr esponding decoding machine's and the programm's parameters. In this wo rk it was demonstrated that DNA four-letter code is optimal, for it al lows the minimal volume of summary cell informational contents. But it is so only for the most simple DNA. Our calculations may inderectly s how that such DNA (and not more complicated) was the object of c proje ctinga at one of the biological evolution's early stages.