True about mycoplasma are all except ?
Correct Answer: They are L forms
Description: Ans. is 'a' i.e., They are L forms Features of mvcoplasma . Mycoplasmas are unique organisms because they have a very small size similar to viruses but unlike viruses, they have an independent existence i.e. they can grow in cell free media. Though they can grow in cell free media but they have a limited biosynthetic ability to they need a rich growth medium containing natural animal protein (usually blood serum) and in most cases a sterol component. . The sterol component is required because mycoplasma contains sterol in their cell membrane. . Mycoplasmas are also unique because they do not have a regular cell wall instead they are bound by a cell membrane consisting primarily of sterol. The absence of the cell wall gives two characteristic propeies to mycoplasma - i) The absence of cell wall makes them highly pleomorphic. ii) Mycoplasmas are completely resistant to penicillin because, they lack the cell wall structure at which penicillin acts instead they are inhibited by tetracycline or erythromycin. Mycoplasma and L forms of bacteria (cell wall defective bacteria) L phase bacteria are cell wall defective bacteria that can replicate serially as non rigid cells and can produce colonies on solid media. . L forms develop when many bacteria either spontaneously or induced by ceain cell wall inhibiting drugs lose pa or all of their cell wall and develop into L forms. Some L phase variants are stable, others are unstable and reve to their bacterial parental forms. It has been suggested that mycoplasmas may represent stable L forms of bacteria but genetic, antigenic and biochemical evidence are against the possibility. . The characteristic of the cell wall defective forms may be similar to those of mycoplasma but by definition, mycoplasmas do not reve to parental bacterial forms or originate from them. There is no genetic relationship between mvcoplasmas and cell wall defective microbial forms or their parent bacteria. About option `d' Mycoplasma and ureoplasma ureolyticum do not produce turbidity in liquid medum. -- www.springerlink.com
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