ABSTRACT
This chapter devotes to scientific aspects of sequence research. Many entries present in the data banks are just variants of the same sequence. Also many sequences are nearly identical because they represent a similar function in organisms that are closely related. All properties of an organism are somehow encoded in its genome, a molecule of nucleic acid that is physically a linear copolymer of four monomers. The chapter argues that the measure of complexity, originates from the statistical theory of signal transmission. It demonstrates once again that the 2-base periodicities in introns are caused by clustering of dinucleotides. The chapter suggests that this might be a reason why introns display lower compositional complexity than exons. It explores that all short oligonucleotides tend to occur in exons in a 3-base periodic manner. For octanucleotides in exons and bacterial genes, it is equal to 0.823 and 0.839, respectively.
