Final answer:
The one-gene, one-enzyme hypothesis arose from studies on the bread mold Neurospora crassa and the fruit fly Drosophila melanogaster, conducted by Beadle and Tatum, which eventually led to the one-gene, one-polypeptide hypothesis.
Step-by-step explanation:
The one-gene, one-enzyme hypothesis emerged from research on two organisms: the bread mold Neurospora crassa and the fruit fly Drosophila melanogaster. In the 1940s, scientists George Beadle and Edward Tatum conducted experiments exposing Neurospora crassa to X-rays to induce mutations. By analyzing the growth of these mutated molds on minimal and complete mediums, they identified links between specific genes and the production of enzymes necessary for the synthesis of vitamins and amino acids. Similarly, experiments with Drosophila melanogaster laid the groundwork for this hypothesis which correlated genetic mutations to enzyme deficiencies. Initially proposed in 1941, this hypothesis later evolved to the one-gene, one-polypeptide hypothesis as a better understanding of the relationship between genes and proteins was achieved.