Griffith conducted an experiment on mice to see the effects of the different types of bacteria. He injected virulent, non-virulent, heat-killed bacteria, and both the non-virulent and heat-killed bacteria, into different mice. He discovered that when the heat-killed bacteria were combined with the non-virulent, the mouse died. Griffith believed that heat-killed bacteria could pass on characteristics to non-virulent bacteria to make it virulent. He believed that this was caused by an unknown “inheritance molecule” that was passed on. He called the passing on of this inheritance molecule transformation. He was the first scientist to record the discovery of an inheritance molecule that could cause transformation. Oswald Avery (1942)
Avery investigated the theory of an inheritance molecule more deeply. He destroyed the lipids, RNA, carbohydrates and proteins of the virulent pneumonia and noticed that transformation still occurred. When he destroyed the DNA, transformation did not occur. Avery concluded that DNA was the inheritance molecule. Avery’s discovery of the inheritance molecule lead to more studies on its jobs, molecular make-up, how it works, and an eventual model made by Watson and Crick. His research opened the doors for many scientists studying DNA. Erwin Chargaff (1940’s)
Erwin Chargaff took samples of DNA from different cells and found that Adenine has almost the same amount as Thymine and Guanine has almost the same amount as Cytosine. This discovery strongly suggested that base-paring existed in DNA, a crucial piece in modeling the structure of DNA. A=T and G=C became known as “Chargaff’s rule”. The discovery of base-pairing made it possible for future scientist to discover and model the structure of DNA. James Watson and Francis Crick (1953)
Watson and Crick used findings of many scientists and compiled them to create a detailed model of the DNA structure that has been called the “most important biological work of the...