PN-curve: A 3D graphical representation of DNA sequences and their numerical characterization

We consider a novel 3D graphical representation of DNA sequences based on the pairs of nucleotides (PNs). The model avoids loss of information accompanying alternative 3D representations in which the curve standing for DNA sequence overlaps or intersects itself. The utility of the method can be illustrated by the examination of similarities/dissimilarities among the complete coding sequence part of beta globin gene of several different species.