Analysis of Apparent 1/ f α Spectrum in DNA Sequences

The question whether the correlations in DNA sequences are long ranged or short ranged is addressed by an extensive analysis of genetic sequences. Our results do not support the notion of critical properties of sequential distribution of nucleotides. Continuous segments of DNA (chromosomes) can be viewed as a mosaic structure of shorter segments with distinct functional role and, consequently, with distinct compositional and sequential characteristics. It is shown that the correlation functions within well-defined sequential entities decay exponentially after one or two hundred nucleotides. The main contribution to the correlations stems from the correlated distributions of repetitions of similar nucleotides. If the analysis of correlations is performed without respect to the borders between functional entities one obtains the signs of long-range correlations.