Chargaff's rule state that the DNA of living organisms have a 1:1 ratio of guanine to cytosine and adenine to thymine. The Chargaff's rule is important to the determination of the structural aspect of DNA because it is responsible for the base pairing rule which specifies how bases are arranged in the DNA structure. The base pairing rule states that Adenine always pair with thymine and guanine always pair with cytosine. These nitrogenous bases pair with each other by means of hydrogen bond.
