Abstract:In order to study the relationship between the second-position base and hydrophobicity when the normal genes become oncogenes, the distance and Y-inner product between codons of oncogene were defined according to the algebraic structure. On GF(7),36 primitive polynomials and their roots were calculated to represent the corresponding biological significance. Based on above definitions, the hydrophobicity change of amino acids for several types of cancers relating to p53 gene were discussed. The results show that the distance between two codons is not smaller than 1when normal genes become oncogenes and the second-positions of codons mutates. When the second-position base of A mutates to G or C, the Y-inner product is negative, while the Y-inner product is larger than 4 when T mutates to G,C or A.