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This Concept Map, created with IHMC CmapTools, has information related to: Answers_External_Bacterial_Structures, Clockwise rotation results in a tumbling motion and changes the direction of bacterial movement. attractants and repellents When the bacterium is exposed to a chemical gradient of a repellent, it tumbles less frequently (has longer runs) as it moves down the gradient, but tumbles at the normal rate if it travels up the gradient. In this way, the net movement is towards a more optimum environment., A basal body consisting of a rod and a series of rings that anchor the flagellum to the cell wall and the cytoplasmic membrane. function of basal body Acts as a rotary molecular motor, enabling the flagellum to rotate and propel the bacterium through the surrounding fluid; powered by proton motive force., flagella function Organelles of locomotion for most bacteria capable of motility., Bacterial Structures External to the Cell Wall ???? glycocalyx (Capsules and Slime Layers), pili (fimbriae) structure and composition The pilus has a shaft composed of a protein called pilin. At the end of the shaft is the adhesive tip structure having a shape corresponding to that of specific glycoprotein or glycolipid receptors on a host cell., A rigid, helical structure that extends from the bacterial surface and composed of the protein flagellin. role in body defense Bacterial flagellin functions as a pathogen-associated molecular pattern or PAMP that binds to pattern-recognition receptors or PRRs on a variety of defense cells of the body and triggers innate immune defenses., glycocalyx (Capsules and Slime Layers) chemical makeup Usually a viscous polysaccharide or polypeptide slime., An outer viscous covering of fibers extending from the bacterium. slime layer Appears as an unorganized, more loosely attached accumulation of gelatinous material., Enables certain bacteria to resist phagocytic engulfment by white blood cells in the body or protozoans in soil and water. in the body May resist unenhanced attachment by phagocytes., Bacterial Structures External to the Cell Wall ???? flagella, flagella flagellar arrangements lophotrichous: Two or more flagella at one or both poles., pili (fimbriae) structure and composition Thin, protein tubes originating from the cytoplasmic membrane; found in virtually all gram-negative bacteria but not in many gram-positive bacteria., Organelles of locomotion for most bacteria capable of motility. benefits of motility Motility serves to keep bacteria in an optimum environment via taxis., Motility serves to keep bacteria in an optimum environment via taxis. taxis A motile response to an environmental stimulus. Bacteria can respond to chemicals (chemotaxis), light (phototaxis), osmotic pressure (osmotaxis), oxygen (aerotaxis), and temperature (thermotaxis)., A motile response to an environmental stimulus. Bacteria can respond to chemicals (chemotaxis), light (phototaxis), osmotic pressure (osmotaxis), oxygen (aerotaxis), and temperature (thermotaxis). rotation of flagella Clockwise rotation results in a tumbling motion and changes the direction of bacterial movement., Organelles of locomotion for most bacteria capable of motility. benefits of motility Motility and chemotaxis probably help some intestinal pathogens to move through the mucous layer so they can attach to the epithelial cells of the mucous membranes. It also enable spirochetes to move through viscous environments and penetrate host cell membranes., Layers of bacterial populations adhering to host cells and embedded in a common capsular mass. benefit to bacteria in the body Bacteria colonize tissue and resist being flushed from the body., An outer viscous covering of fibers extending from the bacterium. capsule Appears as an extensive, tightly bound accumulation of gelatinous material adhering to the cell wall., The pilus has a shaft composed of a protein called pilin. At the end of the shaft is the adhesive tip structure having a shape corresponding to that of specific glycoprotein or glycolipid receptors on a host cell. types short attachment pili (fimbriae), Many bacteria produce a capsular polysaccharide matrix or glycocalyx to form a biofilm. biofilm Layers of bacterial populations adhering to host cells and embedded in a common capsular mass.
