Prokaryotic Cell Structure/FunctionPowerPoint PresentationOBJECTIVESBacterial Cell MorphologyMorphology of Prokaryotic CellsArrangements of CocciBinary Fission-MultiplicationEndosporesEndospore FormationSlide 10EndosporesModern Microbial ClassificationSurvey of ArchaeaStainingGram-Staining PropertySlide 16Gram StainAtypical Cell WallsAcid Fast Cell Walls e.g MycobacteriaAcid-Fast StainCentral Endospores of Bacillus sp.Terminal EndosporesTerminal EndosporesNegative (Capsule) StainFlagellar StainBacterial StructureSlide 27External Structures of ProkaryotesFlagella Structure/FunctionSlide 30Motile CellsAxial FilamentsFimbriae and PiliFimbriae Versus FlagellaPilus Versus FimbriaePiliSlide 37Slime CapsuleSlimeCapsuleStreptococcus pneumoniaeCell Wall StructureProkaryotic Cell WallBacterial Cell WallsComparison of Bacterial Cell Wall StructuresCell Wall TypesGram-Positive Cell WallGram+ Cell WallStructure/Function of PeptidoglycanPeptidoglycanGram-Negative Cell WallOuter MembraneGram-negative Cell WallLPS (Endotoxin)Periplasmic SpaceInternal StructureProkaryotic Cytoplasmic MembraneCytoplasm of ProkaryotesSlide 59Ribosomes- sites of protein synthesisInclusionsTake Home Message: KNOWProkaryotic CellStructure/FunctionMick [email protected] Penal Colony Leatherhead, Surrey, UKOBJECTIVESKnow the shape/structure of bacterial cellsDescribe the functions of specific bacterial structures and their roles in pathogenesis Know the structures that are targeted by antibioticsBacterial Cell Morphology Spherical cells (coccus, cocci) Rod-shaped (bacillus, bacilli) Spiral-shaped, usually motileComma-like CoiledMorphology of Prokaryotic CellsArrangements of CocciBinary Fission-MultiplicationProduced by Gram-positive Bacillus and Clostridium speciesEach vegetative cell transforms into one endosporeEach endospore germinates to form one vegetative cellConstitute a defensive strategy against hostile or unfavorable conditionsEndosporesEndospore FormationEndospore FormationExtremely resistant to drying, heat, radiation and disinfectantsCan remain viable for 10-1000 yearsSerious concern to food industry, hospitalsPotential biological weapons of mass destruction EndosporesSingle celled microbes can belong to any of the three domains of lifeArchaea Prokaryote (no nuclear membrane)Bacteria Prokaryote (no nuclear membrane)Eukarya Eukaryote (nuclear membrane)Modern Microbial ClassificationLack certain molecules (e.g., peptidoglycan)Reproduce by binary fission, budding or fragmentationUnusual shapes existNot known to cause disease in humans or animalsSurvey of ArchaeaSimple stains Differential stains Gram StainAcid-Fast StainSpecial stains Negative (Capsule) StainFlagellar StainFluorescent StainsStaining for Electron MicroscopyStainingGram-Staining PropertyGram-Positive vs. Gram-NegativeGram StainMycoplasmasLack cell wallsSterols in plasma membraneArchaeaWall-less orWalls of pseudomureinMycobacteria/Nocardia: Acid Fast BacteriaAtypical Cell WallsGram stain NOT USED for :Acid Fast Cell Walls e.g MycobacteriaAcid-Fast StainAcid-Fast Bacteria (AFB) resist decolorization with acid-alcohol and stain red, the color of the initial stain, carbol fuchsin.Other bacteria will be decolorized and stain blue with counterstain methylene blue. AFB Examples:Mycobacterium tuberculosisMycobacterium lepraeNocardia asteroidesCentral Endospores of Bacillus sp.Endospore stainFigure 11.9bTerminal Endospores Clostridium botulinum : botulism•Disease is an intoxication by neurotoxin•Clinical sign:–Flaccid paralysisTerminal Endospores Clostridium tetani : tetanusNeurotoxin causes spastic paralysisNegative (Capsule) StainFlagellar StainBacterial StructureXExternal Structures of ProkaryotesFlagellum (Plural: Flagella)Fimbria (Plural: Fimbriae)Pilus (Plural: Pili)Capsule (Plural: Capsules)Responsible for movement3-12 m long, whiplike structures that extend beyond surface of cellMade up of flagellin protein Rotate 360ºFlagella Structure/FunctionArrangements of FlagellaMotile CellsRotate flagella to run or tumbleEx: Helicobacter pylori (Gastric ulcers)Flagella proteins are H antigens (e.g., E. coli O157:H7)EndoflagellaIn spirochetesAnchored at one end of a cellRotation causes cell to move Treponema pallidum (syphilis) Borrelia burgdorferi (Lyme disease)Axial FilamentsFigure 4.10aNonmotile extensionsFimbriae Sticky, hair-like projectionsUsed to adhere/attach May be 100s per cellShorter than flagellaServe an important function in biofilmsFimbriae and PiliNeisseria gonorrhoeaeFigure 3.9Fimbriae Versus FlagellaFigure 3.10Pilus Versus FimbriaeLong hollow tubules made of pilinLonger than fimbriae but shorter than flagellaOne or two per cellJoin two bacterial cells and mediate the transfer of DNA via conjugationAlso known as conjugation pili or sex piliVirulence DeterminantsPiliGlycocalyx (slime)CapsuleExternal Structures of ProkaryotesBacillus anthracisSlime Capsule Loosely attached to cell surfaceProtects cells from drying outPromotes adherence Firmly attached to cell surfaceProtects cells from drying outPromotes adherenceSlime Planktonic= free living bacteriaBiofilm is a community of bacteria surrounded in “slime”(extracellular polysaccharide)Capsule PolysaccharideAntiphagocytic Adherence FactorVirulence FactorAntigenVaccine componentStreptococcus pneumoniae Capsule Pneumonia: Chest X-rayCell Wall StructureProvides structure and shape and protects cell from osmotic forcesAssists some cells in attaching to other cells or in eluding antimicrobial drugsAbsent in animal cellsTarget of important antibioticsProkaryotic Cell WallMost have peptidoglycan Polysaccharide polymer of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)Two basic types: Gram+ and Gram-Bacterial Cell WallsComparison of Bacterial Cell Wall StructuresGram positive:SimpleThick peptidoglycanTeichoic acidsNo outer membraneNo LPS (lipopolysaccharide = endotoxin)Gram negative:ComplexThin peptidoglycanNo teichoic acidsOuter membraneLPS present (lipopolysaccharide = endotoxin)Gram-positiveGram-negativeCell Wall TypesThick layer of peptidoglycanContains unique polysaccharides called teichoic acidsSome linked to lipids, forming lipoteichoic acids that anchor peptidoglycan to cell membraneRetains crystal violet dye in Gram staining procedure; cells appear purpleGram-Positive Bacterium - Cell Wall = Protoplast Gram-Positive Cell WallGram+ Cell WallStructure/Function of Peptidoglycan Mesh-like coat around the cellPolysaccharide