Chargaff's rules
（重定向自Chargaff rules）
Chargaff's rules states that DNA from any cell of all organisms should have a 1:1 ratio (base Pair Rule) of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine. This pattern is found in both strands of the DNA. They were discovered by Austrian chemist Erwin Chargaff.