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The plasma membrane or bacterial cytoplasmic membrane is composed of a phospholipid bilayer and thus has all of the general functions of a cell membrane such as acting as a permeability barrier for most molecules and serving as the location for the transport of molecules into the cell.
Bacterial morphological plasticity refers to changes in the shape and size that bacterial cells undergo when they encounter stressful environments. Although bacteria have evolved complex molecular strategies to maintain their shape, many are able to alter their shape as a survival strategy in response to protist predators, antibiotics, the immune response, and other threats.
The bacterial cell wall differs from that of all other organisms by the presence of peptidoglycan (poly-N-acetylglucosamine and N-acetylmuramic acid), which is located immediately outside of the cytoplasmic membrane. Peptidoglycan is responsible for the rigidity of the bacterial cell wall and for the determination of cell shape. It is ...
Spiral bacteria are another major bacterial cell morphology. [ 2 ] [ 30 ] [ 31 ] [ 32 ] Spiral bacteria can be sub-classified as spirilla, spirochetes, or vibrios based on the number of twists per cell, cell thickness, cell flexibility, and motility.
In bacteria, both nutrients and waste products of metabolism reach the interior of the cell by diffusion, which places an upper limit on the size of these organisms. Cells of the large sulfur bacterium Thiomargarita namibiensis, discovered in 1999, contain a large sac filled with water and nitrates, which pushes most of the cytoplasm close to ...
For the bacterial (prokaryotic) cells that are bounded by a single cell membrane the term "monoderm bacteria" or "monoderm prokaryotes" has been proposed. [4] [8] In contrast to gram-positive bacteria, all archetypical Gram-negative bacteria are bounded by a cytoplasmic membrane as well as an outer cell membrane; they contain only a thin layer ...
The cell wall is important for cell division, which, in most bacteria, occurs by binary fission. This process usually requires a cell wall and components of the bacterial cytoskeleton such as FtsZ. The ability of L-form bacteria and mycoplasmas to grow and divide in the absence of both of these structures is highly unusual, and may represent a ...
A small number of other unusual shapes have been described, such as star-shaped bacteria. [47] This wide variety of shapes is determined by the bacterial cell wall and cytoskeleton and is important because it can influence the ability of bacteria to acquire nutrients, attach to surfaces, swim through liquids and escape predators. [48] [49]