![]() See also: Bacterial genetics Cell division Deoxyribonucleic acid (DNA) Plasmid Genetic diversity and evolution in bacteria is achieved through fast replication, which allows for the accumulation of mutations, as well as the acquisition of foreign DNA from the environment, other bacterial cells, or viruses. The resulting daughter cells will be identical to the parent cell except for the occasional mutation. Each bacterial cell arises by asexual division of a preexisting cell. In addition to the one main, circular chromosome, bacterial cells can carry additional information in smaller, double-stranded circular DNA molecules called plasmids, which replicate independently and confer evolutionary advantages to the cells who carry them. This circular, double-stranded DNA consists of linearly arranged hereditary units, or genes, analogous and sometime homologous with the genes of higher forms of life. Bacterial DNA, which carries the information for synthesis of cell parts, is not linear but circular. See also: Stainingīacteria lack a membrane-bound nucleus, and the deoxyribonucleic acid (DNA) is not separated from the rest of the cell by a membrane but rather exists in a region called nucleoid. Bacterial cytoplasmic structures, including reserve fat, protein, and volutin (a basophilic phosphate substance), are occasionally visible within the bacterial cell. Nonacid fast bacteria will instead stain blue/green in the presence of the counterstain Kinyoun. Bacteria with a high content of mycolic acid in their cell wall, like mycobacteria, stain red. Another type of stain used to identify bacteria is the acid fast stain. Very few “atypical” bacteria do not color at all in a Gram stain test either because they have very few peptidoglycans or because their small size prevents the stain from working effectively. See also: Bacterial growth Bacterial physiology and metabolism Bacteriology Microbiology Prokaryote ![]() One of the few locations in which bacteria are not usually found is within the cells of other healthy organisms, although even this is subject to exceptions for example, there are many bacteria that do live intracellularly in a number of eukaryotic organisms. Dried bacteria, but often still living, can be carried into the air. Each kind of bacterium is fitted physiologically to survive in one of the innumerable habitats created by various combinations of space, food, moisture, light, air, temperature, inhibitory substances, and accompanying organisms. ![]() Bacteria are found almost everywhere, being abundant in soil, water, and the alimentary tracts of animals. Notable exceptions are Thiomargarita namibiensis, 750 micrometers in diameter, and Thiomargarita magnifica, whose cells are so big to be visible with the naked eye. Bacteria (singular bacterium) usually measure 1 to 2 micrometers in diameter and 5 to 10 micrometers in length ( Fig. Relatively simple unicellular (made of only one cell) prokaryotic microorganisms that belong to the domain of life Bacteria. ![]() Some bacteria form resistant structures called endospores, which can survive nutrient depletion and germinate when conditions are more favorable.īacterial cells have different forms (coccus, bacillus, and spirillum) and may be joined together in strings or small groups.īacteria recycle nutrients in the environment and are the main organisms responsible for nitrogen fixation. Further classification into genus and species requires the study of metabolic activity. ![]() Scientists classify bacteria into major groups according to microscopically visible characteristics, such as shape, size, and structure. Bacteria are unicellular prokaryotic microorganisms that belong to the domain of life Bacteria, with generally simpler metabolism as compared to Eukarya and Archaea. ![]()
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