What Genes Do

What Genes Do
Several investigators contributed to our knowledge of what genes do. Garrod is associated with the phrase "inborn error of metabolism" because he suggested that some of his patients had inherited an inability to carry out certain enzymatic reactions. Beadle and Tatum X-rayed spores of Neurospora crassa and found that some of the subsequent cultures lacked a particular enzyme needed for growth on minimal medium. Since they found that the mutation of one gene results in the lack of a single enzyme, they suggested the one gene-one enzyme hypothesis.
Pauling and Itano found that the chemical properties of the (3 (beta) chain of sickle-cell hemoglobin differ from those of normal
hemoglobin, and therefore the one gene-one polypeptide hypothesis was formulated instead. Later, Ingram showed that the bio- chemical change is due to the substitution of the amino acid valine (nonpolar) for glutamate (polar).