Prokaryotes

Cell Structure and Function

Characteristics of Living Things

MetabolismNutrient sourceChemical processes

GrowthResponsivenessReproduction

AsexualSexual

Size Comparison

ComparisonEukaryotesProkaryotes

DNANucleusOther OrganellesCell wallPlasma MembraneOther characteristics

SizeShapeLocation

Prokaryotic Structure & Function Topics

Cell Wall AppendagesCell WallPlasma MembraneCytoplasmDNA regionOrganellesReproductionAntimicrobial actions

Cell Wall AppendagesGlycocalyx

CapsuleSlime Layer

S-layerFlagellaFimbria / Pili

GlycocalyxSecreted by all bacteria in some form

Produced insideExtruded to outside

Aid in survivabilityAid in pathogenicityNegatively chargedComposition

PolysaccharidesPolypetidesBoth

Glycocalyx: CapsuleOrganized repeating units ThickFirmly AttachedFunction

Protect from desiccation and other environmental hazardsEvade host defenses via phagocytosis

Glycocalyx: Slime LayerUnorganizedThinLoosely attachedViscousWater solubleFunction

AdherenceProtectionTrap nutrients

S - Layer

GlycoproteinViscousThinOrganized in crystal latticeAnchored to plasma membraneSome G + and G –

EubacteriaArcheae

FunctionStrengthen and reinforce phospholipid bilayerAdherence

ColonizeResist flushing

ProtectionEnvironmentImmune

BiofimsMicrobial community attached to surfaceResistant

ABImmune

TypesEnvironmentalInfectious

Dental PlaqueEndocarditisKidney StonesCF

FlagellaAppearance

10 -20 micrometersthin

ArrangementPartsFunction

Flagellar ArrangementMonotrichousAmphitrichousLophotrichous

TuftOne or both poles

PeritrichousVariations

Axial FilamentsAtrichous

Flagella ExamplesMonotrichous:

Pseudomonas aeruginosa

Amphitrichous:Spirullum volutans

Lophotrichous: E. coli

Peritrichous:Proteus vulgaris

Flagella

Endoflagellar ArrangementAmphitrichousSpiral around outer membraneAxial Filament rotationCorkscrew motilitySpirochetes

Flagella Anatomy: Exoflagella

Flagellar Parts: ExoflagellaFilament

Flagellin chains in helixHollow core for repairH protein antigen

HookProtein couplingL or curved shapeFunction: rotation

Basal BodyFunction: anchorCentral Protein RodRinged protein structures

4 rings for Gram Negative2 rings for Gram positive

Gram Negative Flagella

Flagellar StainSpecial StainDetermine

PresenceNumberLocation

Stains usedCarbolfuscinPararosanalineWith mordants

Flagellar MotilityRotationATP proton pumpFlagellar Motor

MotAMotBDriven by proton Gradient [outside to inside cell]

Moves toward food sourceClockwise= random movement [tumble]Counterclockwise=forward movement [run]

Motility Tests

Flagella SummaryFunction: Motility

PhototaxisChemotaxisPositive taxisNegative taxis

Proteins allow for classification into groups called serovarsTypes

Endoflagella [spirochetes]Exoflagella Arrangement

MonotrichousAmphitrichousLophotrichousPeritrichous

AnatomyFilamentHookBasal body

PiliPilin proteinThin hollow tubesNumber

Average 1-2Some have up to 10-100

Glycoprotein or glycolipid tipLength varies

Shorter: adherenceLonger: conjugation

Pili Structure

FimbriaGram Negative bacteriaShorter than flagella aka “Short pili”StickyFunction

AdherenceResist flushingBiofilm

Biofilms

Attachment to surface of host tissue or other microbesCell to cell attachmentProduction of extracellular polysaccharides [eps]Planktonic colonization

Conjugation (Sex or F) Pili

Transfer DNA

Cell Wall StructurePeptidoglycan

Complex polysaccharideAlternating AminoSugars

LinkageTransglycolationBeta 1-4 Linkage

StructureNAM (muramic acid)NAG (glucosamine)

CrossbridgeLinkage: TranspeptidasesStructure

TetrapeptideFrom NAMBonded togetherShort chains

Peptidoglycan Structural Unit

Peptidoglycan Linkage

murein

Peptidoglycan Structure Compared

Cell Walls

Gram Positive Cell WallComposition

Thick peptidoglycan 60-90% of cell wallTeichoic acidsLipoteichoic acidsProteins

SurfaceTetrapeptides

FunctionShapePrevent osmotic lysis [peptidoglycan]Teichoic Acids

Polymers of glycerol or ribitolReinforce cell wallIon flowProtectionAntigen Specificity

ProteinsEnzymesAdhesinsInvasins

ExamplesStaphylococcusStreptococcusClostridium

Gram Positive Bacteria

Gram Negative Cell WallComposition

Inner Cell Wall Peptidoglycan

1-2 layers make up 20%Intermediate cross linkageNO teichoic acid

Outer Cell MembraneLipid bilayer

PhospholipidsLipopolysaccharides [LPS]

Lipid AO AntigenCore Polysaccharide connects A-OLPS = Endotoxin

LipoproteinsProteins

Vary based on speciesPorins

FunctionPrevent osmotic lysisSemipermeable Reinforce membrane [LPS]Proteins

AdhesinsEnzymesInvasinsResist phagocytosisPassage of nutrients

ExamplesNeisseriaE coliPseudomonasProteus

Gram Negative Cell Wall

Gram Negative Rods

LPSO Antigen

HexosesAntigenic specificitySmoothness to organism

Core PolysaccharideNAGPhosphorylated sugars [7,8 C]

Lipid ALipopolysaccharideGlucosamine moietiesToxic component

EndotoxinHyrophobicResistant: heat, acidReleased when cell wall disrupted

Cell Wall Comparison

Cell Wall Comparison #2

Gram Stain

Gram Stain Results

Acid Fast Cell WallComposition

PeptidoglycanArabinogalactan linkageGlycolipid: mycolic acidLipids

FreeGlycolipid

LipoarabinomannanPhosphatidyinositol mannosides

PeptidoglycolipidFunctions

Prevent osmotic lysisImpede entry of chemicals

Slower growing organismResistant to phagocytosis

ExamplesMycobacterium tuberculosisMycobacterium lepraeNocardia

Acid Fast Stain

Atypical Cell WallsArchaebacteria

No peptidoglycanPolysaccharidesS-layer [+/-]ProteinsGram +

ThickStain purple

Gram –Protein layerStain pink

Gram positive cell wall

Gram negative cell wall

Periplasm

CompositionGelatinous

LocationBetween peptidoglycan and cytoplasmic membrane

FunctionProteins

Enzymes for nutrient digestion [hyrolytic]Facilitate transfer of nutrientsStorage for toxins to be released into environment

Plasma MembraneComposition

PhospholipidPolarnonpolar

ProteinsIntegralPeripheral+/- polysaccharides

No sterols, hapanoidsFunction

Encloses cytoplasmSelectively permeableETCPeptidoglycan synthesis Aids in DNA replicationFlagella basal protein ringsWaste removalEndospore formation

Plasma Membrane TransportPassive

DiffusionOsmosisFacilitated Diffusion

UniporterChannel Proteins

WaterIons

ActiveAntiporterSymporterATP binding cassette

Gram negative bacteriaPeriplasm proteins

Group TranslocationChemical alterationMembrane impermeableExample: Sugars

GlucoseMannoseFructose

Cytoplasm: CytosolComposition

80% waterProteinsCH20LipidsIons

FunctionMetabolismEnzymes

ExoenzymesEndoenzymes

Organelles of Cytoplasm

Nucleoid regionRibosomesPlasmidsMesosomes

NucleoidComposition

ChromosomeSingle haploid moleculeDouble stranded DNAHelicalSupercoiled around protiens via topoisomerases

FunctionGenomeChemical reactions

Ribosomes: 70SComposition

rRNAProteinSubunits

50S30S

FunctionProtein synthesistRNAmRNA

PlasmidsComposition

DNASmall, helicalDouble strandedIndependent replication5-100 genes1-700 copies in cell

FunctionTypes

R plasmids: AB resistanceF plasmids: Fertility

Protein synthesisUnique proteins

ExotoxinsEndotoxins

Plasmid Replication

Plasmid Transformation

Transposons“Jumping Genes”Composition

DNANucleiodplasmid

FunctionCode for enzymes to transpose

Cut outRe-insert

AB resistance

Transposon cycle

Other OrganellesStorage Granules

SulfurGlycogenVolutin or Metachromic[Phosphate]Nitrogen

Gas vacuolesPhotosynthesisMagnetosomes

MesosomesInfoldings of cytoplasmic membraneConsidered artifact of slide preparation

EndosporesDormant alternate life formsSome Gram positive organismsIdentified

Size: large, smallShape: oval, rectangular, circular, club-shapedLocation : terminal, subterminal, central

ResistantHigh temperaturesDisinfectantsRadiationdrying

SurvivalGermination

Favorable ConditionsSpore coat rupturesVegetative cell forms

Spore StructureResistant coats

CortexSpore coat+/- exosporium

Nucleoid [DNA]RibosomesEnzymes

Spore FormationSporulation

DNA replicatesMembrane septums

One at endOne around DNA [forespore]Both synthesize peptidoglycan to form Cortex [inside layer]Calcium salts addedSpore Coat = keratin around cortexExosporium = outer lipid/protein

Spores: Gram Stain

Bacillus

Clostridium

Spores: Spore Stain

Atypical BacteriaMycoplasmas

Smallest free living cellLack cell wall

[no peptidoglycan]Sterols in cytoplasmic membraneMycolic acid [60%]Examples

Mycoplasma pneumoniaMycoplasma hominis

Atypical BacteriaRickettsia

PleomorphicObligate intracellular parasitesArthropod vectorsExamples

Rickettsia rickettsiitickRMSF

Rickettsia prowazekiiLouseEpidemic Typhus fever

Rickettsia typhiFleaEndemic Typhus fever

Atypical BacteriaChlamydia

CoccoidLack peptidoglycanObligate intracellular parasitesExamples

Chlamydia trachomatisSTD -> PID

Chlamydia pneumoniaEntire air way

Immune SystemCytokines

InterleukinsTNF

Complement ActivationInflammationPhagocytosis

Virulence Factors for Pathogenicity

Capsule [K antigen]Flagella [H antigen]Fimbria/Pili [adhesins]Outer membrane

LPS endotoxinProteins [porins]

Cell Wall PeptidoglycanProteins [A, M, T, R]

Periplasmic Space [enzymes]Plasma membraneEndosporesPlasmidsExotoxins

Enzyme action [hyaluronidase, DNAse, collagenase]Detergents [hemolysins, Staph a-toxinAlter cell metabolism [pertussis, cholera, diptheria toxins]Block Nerve function [tetanus, botulinum toxins]Others: dermonecrotic, erythrogenic

Physical and Chemical Actions on Bacterial Structures

Plasma MembranePolymyxinsDisinfectants: alcohol, chlorhexidine

Ribosomes30S: -cyclines

bind reversibly to distort tRNA/mRNA cannot align

50S: macrolides [-mycin]Bind reversiblyInhibit elongation

Chemical Actions on theBacterial Cell Wall

Summary

Questions?