Prokaryotic Cell Biolog1

Prokaryotic Cell Biolog1 - pilins in pili, flagellins in...

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Prokaryotic Cell Biology - Structures external to the cell membrane = The movement of a prokaryotic flagellum results from rotation of the basal body (see Tortora et al., Figure 4.7) in a manner analogous to an electric motor = The movements of flagellated bacteria alternate between "runs", in which the flagella are all rotating in the same direction and the cell appears to be swimming, and "tumbles" caused by abrupt reversal of flagellar rotation (Tortora et al., Figure 4.8) = By varying the frequency of runs and tumbles, bacteria are able to exhibit taxis in response to positive and negative stimuli = Spirochaetes possess flagella-like axial filaments that are used for locomotion (Tortora et al., Figure 4.9) - Pili and fimbriae are protein filaments, thinner than flagella, found on the surface of some bacteria (Tortora et al., Figure 4.10) = Like the filaments of flagella, pili and fimbriae are composed of helically arranged molecules of a single protein (
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Unformatted text preview: pilins in pili, flagellins in flagella) = The general function of pili and fimbriae is to aid in attachment to surfaces, including tissue Surfaces The shape of a bacterial cell is determined by the cell wall, which serves to protect the cell from osmotic lysis- The major polymer of most bacterial cell walls is peptidoglycan, which forms a continuous network around the cell = One part of peptidoglycan consists of polysaccharide chains composed of repeating units of two monosaccharides, N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) (Tortora et al., Figure 4.11) = Attached to each molecule of NAM is a chain of four amino acids, the "tetrapeptide side chain"; the amino acids include D-isomers, making them different from protein polypeptides = The tetrapeptide side chains are covalently linked, sometimes through additional amino acids, forming a strong three-dimensional network (Tortora et al., Figure 4.12a)...
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This note was uploaded on 01/23/2012 for the course MCB MCB2010 taught by Professor Smith during the Fall '09 term at Broward College.

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