[Symmetry of single-stranded DNA molecules]

A system of so-called coloured symmetry transformations is introduced, in the basis of which all possible symmetry groups of a single strand DNA molecule taken as a genetic text are derived. A strict description of functionally important symmetrical sites, such as palindromes, complementary palindromes, direct repeats is given in terms of the group theory. Possible role of symmetrical fragments in genome is discussed.