The "one gene-one polypeptide" hypothesis, formulated by Beadle and Tatum during their research on the fungus Neurospora crassa, established the relationship between genes and enzymes. According to this hypothesis, each gene controls the synthesis of a specific polypeptide chain, which eventually folds into a functional protein. This means that each gene encodes the instructions to produce a single polypeptide, leading to the synthesis of a specific protein.