An organism possessing a mutation that causes a particular enzyme either not to be synthesized or to be defective in some respect. The reaction that it catalyses therefore does not take place, and, if this reaction is an intermediate step in a metabolic pathway, the subsequent steps in the pathway are also prevented. Such mutants can be induced by various methods, such as irradiation with X-rays, and have proved particularly useful in elucidating the stages of a number of pathways. See also auxotroph. |
