Pili Rigid tubular structure made of pilin protein: Found only in gram-negative cells Function to join bacterial cells for partial DNAtransfer called conjugationCopy right @ The McGraw-Hill Companies, Inc. Permission required for reproduction or displayFimbriaePili16LCarospLphol
16 Pili • Rigid tubular structure made of pilin protein • Found only in gram-negative cells • Function to join bacterial cells for partial DNA transfer called conjugation Fimbriae Pili Copy right © The McGraw-Hill Companies, Inc. Permission required f or reproduction or display . © L. Caro/SPL/Photo Researchers, Inc
FEXGlycocalyxCoating of molecules external to the cell wallmadeofsugarsand/orproteinsTwo types:1. Slime layer - loosely organized and attached2. Capsule - highly organized, tightly attachedCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Slime layer17Capsule(a)(b)
17 Glycocalyx • Coating of molecules external to the cell wall, made of sugars and/or proteins • Two types: 1. Slime layer - loosely organized and attached 2. Capsule - highly organized, tightly attached Slime layer (a) Copyright © The McGraw -Hill Companies, Inc. Permission required for reproduction or display. Capsule (b)
Functionsofthe GlycocalyxProtect cells from dehydration and nutrient lossInhibit killing by white blood cells by phagocytosis.contributing to pathogenicityAttachment-formation of biofilmsCopyright The McGraw-Hill Companies, inc. Permission required for reproduction or displayColonywithoutacapsuleColonieswithacapsuleCell bodyCapsule1818OKathy Park Talaro(b)(a)
18 Functions of the Glycocalyx • Protect cells from dehydration and nutrient loss • Inhibit killing by white blood cells by phagocytosis, contributing to pathogenicity • Attachment - formation of biofilms Colony without a capsule Colonies with a capsule © Kathy Park Talaro Capsule Cell body © John D. Cunningham/Visuals Unlimited (a) (b) Copyright © The McGraw -Hill Companies, Inc. Permission required for reproduction or display. 18
McGrawBiofilm FormationHicleanabioticsurface0DPlayAudioTextPauseClean abiotic surfaces immersed in liquidtend to attractandconcentrate nutrients whereas biotic surfaces such as plant or animaltissuecanthemselves be a source of nutrients formicroorganisms19CopyrightTheMcGraw-Hill Companies,Inc
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BiofilmonacatheterCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or dis playCathetersurfaceFungalcellsStaphylococci20Janice Carr/CDC
Catheter surface Staphylococci Fungal cells Biofilm on a catheter 20 Janice Carr/CDC Copyright © The McGraw -Hill Companies, Inc. Permission required for reproduction or display