![]() ![]() The morphological diversity of gram-positive (monoderm) and gram-negative (diderm) bacteria is markedly different. The vibrio cell shape is formed by the limitation one-sided growth and, for a number of physical reasons, it appears to be the most effective form for chemotaxis. Filamentous and branching forms can probably be considered an adaptation for an increase in the nutrient-absorbing surface area of the cell, and it is also beneficial for fixing in the soil, functional differentiation, swarming, etc. ![]() One possible advantage of such a shape is effective movement in viscous media, including the internal media of other living organisms. Cocci presumably formed as a result of the loss of some cytoskeletal proteins or are the result of “reductive division.” A spiral shape can form as a result of controlled lysis of some cross-linked peptide chains between the glycan strands of the peptidoglycan, or it can be maintained simply due to the spirally oriented elements of the cytoskeleton. Most researchers are of the opinion that rods are the ancestral form of all other shapes of bacterial cells. Why are they rods, cocci, spiral and filamentous? A number of studies have shown that the rod shape seems to be the optimal in some of the most important parameters, e.g., the efficiency of intracellular transport and active movement in aquatic environment. Therefore, on one hand, there is a wide morphological diversity of bacteria, and, on the other hand, a certain shape is strictly defined for one or another group of them. ![]() The bacterial cell shape and size are influenced by many selective forces. ![]()
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