AP BIOLOGY

Detailed explanation-1: -Chargaff rule : The rule that in DNA there is always equality in quantity between the bases A and T and between the bases G and C. (A is adenine, T is thymine, G is guanine, and C is cytosine.) Named for the great Austrian-American biochemist Erwin Chargaff (1905-2002) at Columbia University who discovered this rule.

Detailed explanation-2: -Further a 1:1 stoichiometric ratio of purine and pyrimidine bases (i.e., A+G=T+C ) should exist. This pattern is found in both strands of the DNA. They were discovered by Austrian-born chemist Erwin Chargaff, in the late 1940s.

Detailed explanation-3: -Chargaff’s realization that A = T and C = G, combined with some crucially important X-ray crystallography work by English researchers Rosalind Franklin and Maurice Wilkins, contributed to Watson and Crick’s derivation of the three-dimensional, double-helical model for the structure of DNA.

Detailed explanation-4: -15495. Erwin Chargaff found that in DNA, the ratios of adenine (A) to thymine (T) and guanine (G) to cytosine (C) are equal.

Detailed explanation-5: -Erwin Chargaff Besides, in his career, he discovered two major rules that helped the discovery of the double helix structure of the DNA. According to his first rule, the DNA is the number of cytosine unit is equal to the guanine unit. In addition, the number of thymine unit is equal to the adenine units.