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Gram-positive bacteria have a thick peptidoglycan layer in their cell wall, which retains the crystal violet during Gram staining, resulting in a purple color. Gram-negative bacteria have a thin peptidoglycan layer which does not retain the crystal violet, so when safranin is added during the process, they stain red.
This causes the bacteria to form filaments, elongated cells that lack internal cross-walls. [10] After a period of time, the cell walls of the filaments are digested, and the bacteria collapse into very large spheres surrounded by just their cytoplasmic and outer membranes.
Since the cell wall is required for bacterial survival, but is absent in some eukaryotes, several antibiotics (notably the penicillins and cephalosporins) stop bacterial infections by interfering with cell wall synthesis, while having no effects on human cells which have no cell wall, only a cell membrane.
Mycoplasma is a genus of bacteria that, like the other members of the class Mollicutes, lack a cell wall, and its peptidoglycan, around their cell membrane. [1] The absence of peptidoglycan makes them naturally resistant to antibiotics such as the beta-lactam antibiotics that target cell wall synthesis.
Mycoplasma pneumoniae is a species of very small-cell bacteria that lack a cell wall, in the class Mollicutes. M. pneumoniae is a human pathogen that causes the disease Mycoplasma pneumonia, a form of atypical bacterial pneumonia related to cold agglutinin disease.
Mollicutes is a class of bacteria [2] distinguished by the absence of a cell wall. The word "Mollicutes" is derived from the Latin mollis (meaning "soft" or "pliable"), and cutis (meaning "skin"). Individuals are very small, typically only 0.2–0.3 μm (200–300 nm ) in size and have a very small genome size .
A cell wall is a structural layer that surrounds some cell types, found immediately outside the cell membrane.It can be tough, flexible, and sometimes rigid. Primarily, it provides the cell with structural support, shape, protection, and functions as a selective barrier. [1]
As in other organisms, the bacterial cell wall provides structural integrity to the cell. In prokaryotes, the primary function of the cell wall is to protect the cell from internal turgor pressure caused by the much higher concentrations of proteins and other molecules inside the cell compared to its external environment.