Erwin Chargaff

To understand the DNA molecule better, scientists were trying to make a model to understand how it works and what it does. In the 1940’s another scientist named Erwin Chargaff found the pattern in the amounts of the four bases: adenine, guanine, cytosine, and thymine.

He took samples of DNA of different cells and found that the amount of adenine was almost equal to the amount of thymine, and that the amount of guanine was almost equal to the amount of cytosine. Thus you could say: A=T, and G=C. This discovery later became Chargaff’s Rule.