The goal of the experiment was to either support or reject the null hypothesis, which states that “genes do not have a one-to-one correspondence with enzymes.” The findings indicated that “the one-gene, one-enzyme hypothesis is supported.”
The experiment was set up focused on three different mutant strains of Neurospora crassa, which were put in differential environments. The mutant was unable to synthesize arginine, and thus, the environment categories either had arginine or its precursor molecules, such as citrulline and ornithine. It is important to point out that change from one precursor to the next one requires one specific enzyme, such as enzyme 1. Enzyme 1, enzyme 2, and enzyme 3 produce ornithine, citrulline, and arginine, respectively.
The results showed that none of the mutants were able to grow in the environment with no arginine and its precursors. Only a mutant with no enzyme 1 was able to grow in an ornithine-only environment. In a citrulline-only environment, mutants with no enzyme 1 or enzyme 2 were able to grow. In an arginine-only environment, all three mutants were able to grow. In other words, each gene has a correspondence to each enzyme type, which supports the null hypothesis because defects in the gene result in a lack of one key enzyme.