Erwin Chargaff was a biochemist who discovered two rules that helped lead to the discovery of the double helix structure of DNA. Chargaff noticed the amounts of adenine, thymine, cytosine, and guanine there was in the DNA of many different species. Chargaff used the information he found about these four base molecules and he publish his data in 1950. Chargaff noticed that the amount of thymine in DNA was the nearly equals the amount of adenine, and the amount of cytosine nearly equals the amount of guanine. This finding is known as Chargaff's rule and it is shown as C=G and T=A. This evidence of molecular diversity, had been presumed absent from DNA, made DNA a more credible candidate for genetic material than protein. With DNA being seen as the more possible reason for the transfer of genetic material, scientists were able to focus more on the structure if DNA and they could start making models.

Erwin Chargaff