<prompt> Chargaffs rule state that, in DNA ?Purines to pyrimidines ratio is 2ATGCPurines PyrimidinesAll of the above  <response>: Ref : Harper 291he p. 344 28thie p. 302; Essentials of biochemistry p. 915Chargaffs rule states that in DNA of all species quantities of ourines is the same as that of pyrimidines, i.e. AG TC. In A Gother words, ratio of purines to pyrimidines is one, i.e. T c - 1This is because one member of a base pair in a DNA must always be a purine and the other a pyrimidine.This base pairing restriction explains that in a double stranded DNA molecule, the content of adenine equals that of thymineAT and the content of guanine equals that of cylosine GC. Therefore 7 or AC TG 