The following organism is motile with NO external flagella
Correct Answer: Spirochetes
Description: (D) Spirochetes # Spirochetes: Elongated, motile, flexible bacteria twisted spirally along the long axis are termed 'spirochetes' (from Speira, meaning coil and chaite, meaning hair). They are structurally more complex than other bacteria. A characteristic feature is the presence of varying numbers of endoflagella, which are polar fiagella wound along the helical protoplasmic cylinder, and situated between the outer membrane and cell wall. Endoflagella are believed to be responsible for motility but the exact mechanisms of locomotion are not understood.> Brucellae are coccobacilli or short rods 0.5-0.7 urn x 0.6-1.5 pm in size, arranged singly or in short chains. The cells are so small that they may be mistaken for cocci, as was done by Bruce who called them Micrococcus melitensis. In older cultures, irregular forms appear. They are nonmotile, noncapsulated and nonsporing. They are Gram negative and nonacid fast. Bipolar staining is not uncommon.> Mycoplasmas are the smallest free-living microorganisms, and one of the most pleomorphic.They occur as granules and filaments of various sizes. The granules may be coccoid, balloon, disc, ring or star forms. The filaments are slender, of varying lengths and show true branching. Multiplication is by binary fission, but as genomic.> Chlamydiae occur in two forms, the elementary body and the reticulate body (formerly also called the 'initial body'). The elementary body is the extracellular, infective form. It is a spherical particle, 200-300 nm in diameter, with a rigid trilamirar cell wall similar to the cell walls of Gram negative bacteria, and an electron dense nucleoid. The reticulate body is the intracellular growing and replicative form, 500- 1000 nm in size. Its cell wall is fragile and pliable, leading to pleomorphism.
Category:
Microbiology
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