Finding how genes dictate phenotypes

- In 1902, British physician Archibald Garrod first suggested that genes dictate phenotypes through enzymes that catalyze specific chemical reactions​ - He thought symptoms of an inherited disease reflect an inability to synthesize a certain enzyme​ - Cells synthesize and degrade molecules in a series of steps, a metabolic pathway​ - Experiments were made that used mutants and found that they lacked different enzymes that were needed for synthesizing a certain molecule - The results of the experiments provided support for the one gene–one enzyme hypothesis​ - The hypothesis states that the function of a gene is to dictate production of a specific enzyme​ - Not all proteins are enzymes, so researchers later revised the hypothesis: one gene–one protein​, and after realizing that proteins are made of several polypeptides (polymer for protein, each has their own gene) they revised the hypothesis to the one gene - one polypeptide hypothesis - but it is common to refer to gene products as proteins rather than more precisely as polypeptides​