Bacterial adherence to epithelium is mediated through:
Ans: B (Fimbriae) Ref: Ananthnarayan R. Paniker CKJ. Textbook of Microbiology. 8th Edition. Hyderabad: Universities Press: 2009. Pg. 18-21.Explanation:FimbriaeCertain (Tram-negative bacilli carry very fine, hair-like surface appendages called fimbriae or pili. They are shorter and thinner than flagellaFimbriae can be seen only under the electron microscope.Fimbriae function as organs of adhesion, helping the cells to adhere firmly to particles of various kindsFimbriated bacteria form surface pellicles in liquid media.Many fimbriated cells (for example Escherichia, Klebsiella) agglutinate red blood cells.Hemagglutination provides a simple method of detecting the presence of such fimbriae. The hemagglutination is specifically inhibited by D- mannose (mannose sensitive)A special type of fimbria is the sex pili. They are found on 'male' bacteria and help in the attachment of those cells to 'female' bacteria. They do not mediate attachment to epitheliumFlagellaFlagella are the organs of locomotion.Flagellum consists of three distinct parts the filament, the hook and the basalFlagella are made up of a protein (flagellin)Flagella are less than 0.02 Jim in thickness and hence beyond the limit of resolution of the light microscope. They may, in some instances, be seen under dark ground illumination.They can be visualised by special staining techniques in which their thickness is increased by mordanting, or by electron microscopyMesosoxnesMesosomes (chondroids) are vesicular, convoluted or niultilaniinated structures formed as invaginations of the plasma membrane into the cytoplasm.They are more prominent in Gram-positive bacteria.They are the principal sites of respiratory enzymes in bacteria and are analogous to the mitochondria of eukaryotes.Mesosomes are often seen in relation to the nuclear body and the site of synthesis of crosswall septa, suggesting that they coordinate nuclear and cytoplasmic division during binary fission.
Sex pili
Fimbriae
Flagella
Mesosomes
Morphology and Physiology of Bacteria