However, sterols only exist in the cytoplasmic membranes of eukaryotes while in prokaryotes , virtually all do not have sterol in their membranes except mycoplasmas , a group of cell wall-less bacteria. A hot, sulfur-rich, generally acidic environment, commonly inhabited by hyperthermophilic Archaea . A harmful derivative of oxygen capable of oxidative destruction of cell components. A mutation that restores wild-type phenotype without altering the original mutation, usually arising by mutation in another gene . A nutritional situation in which two or more organisms combine their metabolic capabilities to catabolize a substance not capable of being catabolized by either one alone.
Infection generally occurs by direct contact with lesions of syphilis.