Abstract: The first exon of DNA primary sequence such as β-globin gene was translated into “structure graph” based on the rules suggested in this paper. Then the invariants, such as molecular connectivity indices, were extracted from those graphic representations of DNA primary sequences, and used to calculate the similarities among the ten species. From these similarities/dissimilarities the homologies can be revealed that they are in agreement]with the phylogenetic tree satisfactorily.

Key words: DNA primary sequence, Exon, Molecular connectivity index, Similarity comparison, Phylogenetic tree