The one gene–one enzyme hypothesis states that each gene directs the synthesis of a particular chain of protein.
In the 1940's experiments by George W. Beadle (1903-1989) and Edward L. Tatum (1909-1975) led to the hypothesis that one gene on DNA coded for one kind of enzyme. Later research recognized that not all proteins are enzymes. Insulin and keratin, hair's structural protein are both gene and protein products.
The one gene–one enzyme hypothesis was then changed to say that one gene led to one type of protein. After it was discovered that proteins could be made up of more than one kind of polypeptide chain, Beadle and Tatum’s idea was restated as the one gene–one polypeptide hypothesis.
Of interest, new research suggests that cochlear implants and gene therapy in humans could restore hearing to the deaf. Scientists have been able to restore tonal hearing in guinea pigs with the new gene delivery method. Find out more from the Los Angeles Times.