Some restriction enzyme recognition sites are not necessarily rotationally symmetrical. For example, the enzyme btg i cleaves dna at the site 5' c^crygg, where the symbol ^ represents the cleavage site, r= either purine, and y = either pyrimidine. Make the simplifying assumptions that equal amounts of each of the four bases exist in the human genome and that the base sequence is random. What fraction of the btg i sites in the human genome would you expect to have rotational symmetry?.
