The Tenericutes contain a single class named Mollicutes. This class of bacteria lacks a cell wall and are some of the smallest organisms known. Tenericutes are also known as Mycoplasmas and are phylogenetically related to the Firmicutes.  Mycoplasmas are resistant to osmotic lysis which is in part due to sterols. Sterols make the cytoplasmic membranes of Mycoplasma more stable than any other bacterial cytoplasmic membrane.  Some Mycoplasmas contain lipoglycan. Lypogycans are embedded in the cytoplasmic membrane and function in helping stabilize the membrane. They have also been associated with aiding mycoplasmas attachment to the surface of animal cells.

The growth of Mollicutes is not hindered by antibiotics that inhibit cell wall synthesis, as it has no cell wall, but they are hindered by antibiotics that target other cell structures. Most mycoplasmas growth factors include amino acids, purines, vitamin and carbohydrates as carbon and energy sources. The genus Spiroplasma are composed of helical shaped Mollicutes. Though they lack flagella and a cell wall they are able to move by means of rotary motion or slow undulation.