Bacteria of Morphology
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Bacteria
of
Morphology
Bacteria display a wide diversity of shapes and sizes, called morphologies. Bacterial cells are about ten times smaller than eukaryotic cells and are typically 0.5-5 micrometres in length. However a few species, for example Thiomargarita namibiensis and Epulopiscium fishelsoni, are up to half a millimetre long and visible to the unaided eye. Among the smallest bacteria are members of the genus Mycoplasma which measure only 0.3 micrometres, as small as the largest viruses. Most bacterial species are either spherical, called coccus (pl. cocci, from Greek kókkos, grain, seed) or rod-shaped, called bacillus (pl. bacilli, from Latin baculus, stick). Some rod-shaped bacteria, called vibrio, are slightly curved or comma-shaped, while others, called spirilla, form twisted spirals. This wide variety of shapes are determined by the bacterial cell wall and cytoskeleton. These different shapes are important as they can influence the ability of bacteria to acquire nutrients, attach to surfaces, swim through liquids or escape predation. Many bacterial species exist simply as single cells, while others tend to associate in diploids (pairs), characteristic for example Neisseria, or chains, such as Streptococcus, while members of the genus Staphylococcus, form characteristic "bunch of grapes" clusters. Bacteria can also be elongated to form filaments, for example the Actinobacteria. Filamentous bacteria are often surrounded by a sheath which contains many individual cells, and certain species, such as the genus Nocardia, form complex, branched filaments, similar in appearance to fungal mycelia.
Bacterial species differ in the number and arrangement of flagella on their surface; some have a single flagellum ( monotrichous), a flagellum at each end ( amphitrichous), clusters of flagella at the poles of the cell ( lophotrichous), while others have flagella distributed over the entire surface of the cell ( peritrichous). The bacterial flagella is the best-understood motility structure in any organism and is made of about 20 proteins, with approximately another 30 proteins required for its regulation and assembly. The flagellum is a rotating structure driven by a motor at the base that uses the proton-motive force for power. This motor drives the motion of the filament, which acts as a propeller. Many bacteria (such as E. coli) have two distinct modes of movement: forward movement (swimming) and tumbling. The tumbling allows them to reorient and makes their movement a three-dimensional random walk. (See external links below for link to videos.)
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Kumkum / safron - Crocus sativus
Crocuses belong to the family Iridaceae. The saffron crocus is classified as Crocus sativus, It is a shrub. Leaves are seen towards the base of the stem and are compactly arranged.Read More about safron.....
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