All of us are informed protein is an essential substance to maintain life. However, how protein is produced and what is the relationship between DNA and protein are still in the air.
In 1902, Neurospora was acted as experimental subject by AG to confirm his hypothesis about a human disease, alcaptonuria that was caused an enzyme inactivate generated through using mutagens to introduce mutation into genes as a result of a substrate accumulate abnormally. Therefore, a defective gene gives a defective enzyme. In other words, a gene seemed to be responsible for making one enzyme.
