FlagellarResponsesGuide bacteria ina direction in response to external stimulusChemical stimuli - chemotaxis; positive and negativeLight stimuli - phototaxisSignal sets flagella into motion clockwise or counterclockwise:Counterclockwise - results in smooth linear direction -runClockwise-tumblesCopyright The McGraw-Hill Comparies, Inc. Permission required for reproduction or displayKeyTumble (T)Run (R)Tuble ()11(a)No attractant(b)Gradientofattractantconcentrationorrepellent
11 Flagellar Responses Guide bacteria in a direction in response to external stimulus: Chemical stimuli – chemotaxis; positive and negative Light stimuli – phototaxis Signal sets flagella into motion clockwise or counterclockwise: Counterclockwise – results in smooth linear direction – run Clockwise – tumbles Run (R) Key Tumble (T) T T Tumble (T) (b) Gradient of attractant concentration T T R R Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (a) No attractant or repellent
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Periplasmic FlagellaCopyright The McGraw-Hill Companies, Ihc. Permission required for reproduction or display Internal flagellaPFosPCenclosed in thespace between the(a)outer sheath and theOutersheath(OS)cell wallpeptidoglycanProtoplasmiccylinder (PC)Periplasmicflagella (PF)ProducecellularPeptidoglycanmotility by contractingand impartingtwisting or flexingCellmembranemotion(b)13
13 Periplasmic Flagella • Internal flagella, enclosed in the space between the outer sheath and the cell wall peptidoglycan • Produce cellular motility by contracting and imparting twisting or flexing motion (b) (a) Cell membrane PF PC OS Periplasmic flagella (PF) Outer sheath (OS) Protoplasmic cylinder (PC) Peptidoglycan Copyright © The McGraw -Hill Companies, Inc. Permission required for reproduction or display
TheMcGraw-Hill CompaniesConceptCheck:Which of the followingbest describes the action oftheprokaryotic flagellum?A.It whips back and forth to move the cellB.It extends an contracts to move the cellC.It rotates to move the cellD.It attaches to the environment and pulls the cellE.It is capable of all of the above14
Concept Check: Which of the following best describes the action of the prokaryotic flagellum? A. It whips back and forth to move the cell B. It extends an contracts to move the cell C. It rotates to move the cell D. It attaches to the environment and pulls the cell E. It is capable of all of the above 14
FimbriaeCopyright The McGraw-Hill Companies, Ihc. Permission required for reproduction or display..Fine,proteinaceous,hairlike bristlesemerging from thecell surfaceFunction in adhesionto other cells andoEyeafSciencePn(a)surfacesEcolicellsIntestinalmicrovilli15Dr. S.Knutlon from D.R. Lloyd and S. Knutton, Infeclion and Immunity, January 1987, p 88-92. ASM(b)
E. coli cells Intestinal microvilli G 15 Fimbriae • Fine, proteinaceous, hairlike bristles emerging from the cell surface • Function in adhesion to other cells and surfaces (a) (b) Copyright © The McGraw -Hill Companies, Inc. Permission required for reproduction or display. © Eye of Science/Photo Researchers, Inc. Dr. S. Knutton from D.R. Lloyd and S. Knutton, Infection and Immunity, January 1987, p 86-92. © ASM