peroⅪsome Enzyme-filled vesicle in which fatty acids and amino acids are digested first into hydrogen peroxide(which is toxic), then to harmless products vesicle vesicula, little bladder] Within the cytoplasm of cells, one of a variety of small membrane-bound sacs that function in the transport, storage, or digestion of substances or in some other activityperoxisome Enzyme-filled vesicle in which fatty acids and amino acids are digested first into hydrogen peroxide (which is toxic), then to harmless products. vesicle [L. vesicula, little bladder] Within the cytoplasm of cells, one of a variety of small membrane-bound sacs that function in the transport, storage, or digestion of substances or in some other activity