Competitive Reactions and Antagonisms in the Biosynthesis of Amino Acids by Neurospora

The interpretation that the only effect of a specific mutation is to alter a single reaction in the synthesis of an essential metabolite has sometimes been understood in too narrow a sense. This idea, usually called the one gene-one enzyme hypothesis, refers to the primary, or direct effect of the gene on its immediate environment. Numerous side effects resulting from the initial impact of the gene are to be expected on this interpretation, and such secondary events may be confused with the primary, genecontrolled reaction itself. Workers in the immediate field have long been aware of the possibility of such confusion, but a more complete statement about events directly and indirectly resulting from the action of genes is desirable. The competitions and antagonisms occurring in the synthesis of amino acids in Neurospora not only offer the opportunity of doing this, but they cannot be readily understood without it.