STUDIES ON THE ORIGIN OF YEAST MITOCHONDRIA

Abstract

Torulopsis utilis was grown aerobically and anaerobically and the influence of the growth conditions on mitochondrial structure and enzyme content studied. The aerobic cells contain mitochondria which are structurally and enzymically similar to those of other yeasts and higher organisms. However the anaerobic cells were found to be devoid of mitochondria but to contain an extensive cytoplasmic membrane system which is not present in aerobic cells. This previously un-described membrane system appears to be of two types one is a multimembrane system resembling the well known myelin forms, consisting of a number of unit membranes closely adjacent to one another; and the other is a membrane system reminiscent of the endoplasmic reticulum of higher organisms. In addition the anaerobic cells are devoid of the mitochondrial cytochrome enzymes but the cytoplasmic membranes contain some of the enzymes normally associated with the mitochondrial membranes. Evidence is presented to indicate that on aeration of the anaerobic cells the synthesis of the cytochrome enzymes is induced and the cytoplasmic membrane system is organized into the mitochondria of the aerobic cell.