BIO 411BIO 411Chapter 3 – Bacterial Morphology Chapter 3 – Bacterial Morphology

and Cell Wall Structure and and Cell Wall Structure and SynthesisSynthesis

Prokaryote vs. EukaryoteProkaryote vs. Eukaryote Get with a partner and make a list of the Get with a partner and make a list of the

differences between Prokaryotes and differences between Prokaryotes and Eukaryotes.Eukaryotes.

List differences on boardList differences on board Amazing cell size demo!Amazing cell size demo!

Shapes of BacteriaShapes of Bacteria Almost all bacteria have one of three Almost all bacteria have one of three

morphologies (or shapes):morphologies (or shapes): coccus - spherical-shaped (pl., cocci)coccus - spherical-shaped (pl., cocci)

DiplococcusDiplococcus StreptococcusStreptococcus StaphylococcusStaphylococcus

bacillus - rod-shaped (pl., bacilli)bacillus - rod-shaped (pl., bacilli) spirillum - spiral-shaped (pl., spirilla)spirillum - spiral-shaped (pl., spirilla)

Figure 3-3 BFigure 3-3 B

Gram StainGram Stain

Gram StainGram Stain Crystal violetCrystal violet IodineIodine Decolorizer (EtOH or Acetone)Decolorizer (EtOH or Acetone) SafraninSafranin

Gram + vs. Gram – cellsGram + vs. Gram – cells ““P” – purple, positiveP” – purple, positive Figure 3-3 AFigure 3-3 A

Only dependable on new cultures (24hr)Only dependable on new cultures (24hr)

Bacterial Cell StructureBacterial Cell Structure Typical prokaryotic cell - Figure 3.1Typical prokaryotic cell - Figure 3.1 Inside-Out ApproachInside-Out Approach What is the cytoplasm?What is the cytoplasm? ~80% water~80% water

CytoplasmCytoplasm Also contains:Also contains:

The bacterial chromosome (structure?)The bacterial chromosome (structure?) It is about 1mm long (1000X longer than the cell)It is about 1mm long (1000X longer than the cell) It’s localized in the nucleoidIt’s localized in the nucleoid

Plasmids – small circular pieces of non-Plasmids – small circular pieces of non-chromosomal DNAchromosomal DNA Functions?Functions?

Ribosomes (70S) – function?Ribosomes (70S) – function? Protein synthesisProtein synthesis

CytoplasmCytoplasm Cytoplasmic membrane – typical lipid Cytoplasmic membrane – typical lipid

bilayerbilayer Carries out many functions associated with Carries out many functions associated with

eukaryotic organelleseukaryotic organelles

Mesosome – anchor to separate daughter Mesosome – anchor to separate daughter chromosomes during cell divisionchromosomes during cell division

Figure 3-1Figure 3-1

Bacterial Cell Structure (cont.)Bacterial Cell Structure (cont.)

Next layer:Next layer: Bacterial Cell Wall Bacterial Cell Wall Composed of sub-units found nowhere Composed of sub-units found nowhere

else in natureelse in nature site of action of some of the most site of action of some of the most

effective antibioticseffective antibiotics cell wall determines a cell’s morphologycell wall determines a cell’s morphology Primary Function – protect cell from Primary Function – protect cell from

exploding (osmotic pressure)!!!exploding (osmotic pressure)!!!

Bacterial Cell Structure (cont.)Bacterial Cell Structure (cont.) Cell Wall StructureCell Wall Structure

Bacterial cell walls are composed of Bacterial cell walls are composed of peptidoglycanpeptidoglycan the the glycanglycan portion of peptidoglycan is made of a portion of peptidoglycan is made of a

huge polymer of carbohydrates containing:huge polymer of carbohydrates containing: N-acetylmuramic acid (NAN-acetylmuramic acid (NAMM) and) and N-acetylglucosamine (NAN-acetylglucosamine (NAGG)) These long chains of alternating NAM and NAG These long chains of alternating NAM and NAG

are held together by short are held together by short peptidepeptide cross-bridges cross-bridges log raft analogylog raft analogy

Gram+ vs. Gram- Cell WallsGram+ vs. Gram- Cell Walls Gram+ cells have a very thick, multilayered Gram+ cells have a very thick, multilayered

cell wallcell wall they also contain they also contain teichoic acids teichoic acids andand lipoteichoic lipoteichoic

acidsacids LysozymeLysozyme Figure 3-2 AFigure 3-2 A

Gram- cells have a very thin layer of Gram- cells have a very thin layer of peptidoglycanpeptidoglycan they also have an they also have an outer membraneouter membrane in addition to in addition to

the cytoplasmic membranethe cytoplasmic membrane the space between these two membranes is called the space between these two membranes is called

the the periplasmic spaceperiplasmic space or or periplasmperiplasm

Gram+ vs. Gram- Cell Walls (cont.)Gram+ vs. Gram- Cell Walls (cont.) the outer membrane is an asymmetric bilayer:the outer membrane is an asymmetric bilayer:

Phospholipids on the insidePhospholipids on the inside lipopolysaccharideslipopolysaccharides (LPS) on the outside (LPS) on the outside

LPS structure:LPS structure: Lipid A - also called Lipid A - also called endotoxinendotoxin because it because it

damages cells and tissues (also causes fever damages cells and tissues (also causes fever and shock)and shock)

Core PolysaccharideCore Polysaccharide O antigen – distinguishes serotypes of a O antigen – distinguishes serotypes of a

species (species (E. coliE. coli O157O157:H7):H7) Figure 3-10Figure 3-10

Gram+ vs. Gram- Cell Walls (cont.)Gram+ vs. Gram- Cell Walls (cont.) PorinsPorins allow non-specific transport across the allow non-specific transport across the

membranemembrane Figure 3-2 BFigure 3-2 B

Basis for the Gram stain reaction (Figures 3-2 Basis for the Gram stain reaction (Figures 3-2 and 3-3 A)and 3-3 A)

Bacterial Cell StructuresBacterial Cell Structures CapsuleCapsule outer coating of sticky outer coating of sticky

polysaccharide or proteinpolysaccharide or protein Also called a Also called a glycocalyxglycocalyx or or slime layerslime layer Functions?Functions?

Antiphagocytic and poorly antigenic - Antiphagocytic and poorly antigenic - Streptococcus pneumoniaeStreptococcus pneumoniae

Adherence - Adherence - Streptococcus mutansStreptococcus mutans and and dental caries, many other examples too!dental caries, many other examples too!

Biofilm - protectionBiofilm - protection

Movement of Prokaryotic CellsMovement of Prokaryotic Cells FlagellaFlagella - ropelike propeller composed of - ropelike propeller composed of

flagellinflagellin ChemotaxisChemotaxis

bacteria can move toward nutrients or away bacteria can move toward nutrients or away from toxic substancesfrom toxic substances

Mechanism – “swim and tumble”Mechanism – “swim and tumble”

Attachment of Prokaryotic CellsAttachment of Prokaryotic Cells Bacteria can use Bacteria can use fimbriaefimbriae and and pilipili to attach to attach

to surfaces and other cellsto surfaces and other cells fimbriae are numerous, short protein fimbriae are numerous, short protein

filaments of attachment (filaments of attachment (E. coliE. coli and and Neisseria gonorrhoeaeNeisseria gonorrhoeae))

pili are long protein filaments for attachment pili are long protein filaments for attachment of bacteria to other bacterial cellsof bacteria to other bacterial cells Used for DNA transferUsed for DNA transfer

Figure 3-4Figure 3-4

Mycobacteria and MycoplasmasMycobacteria and Mycoplasmas Mycobacteria have a peptidoglycan cell Mycobacteria have a peptidoglycan cell

wall, but they contain an outer covering wall, but they contain an outer covering of mycolic acidof mycolic acid AntiphagocyticAntiphagocytic Acid-fast stainAcid-fast stain

Mycoplasmas do not have a cell wallMycoplasmas do not have a cell wall

Bacterial EndosporesBacterial Endospores Some types of Gram+ bacteria have the Some types of Gram+ bacteria have the

ability to form ability to form endosporesendospores Primary genera Primary genera BacillusBacillus and and ClostridiumClostridium the endospore is the “navy seal” of living the endospore is the “navy seal” of living

organismsorganisms

Vegetative State vs. EndosporeVegetative State vs. Endospore Endospore production – Figure 3-12Endospore production – Figure 3-12

Bacterial Endospores (cont.)Bacterial Endospores (cont.) Endospore germinationEndospore germination Important Point:Important Point:

endospores endospores are notare not a means of reproduction a means of reproduction

Importance of endosporesImportance of endospores

Disease of the DayDisease of the Day AnthraxAnthrax Etiology – Etiology – Bacillus anthracis Bacillus anthracis (via toxins)(via toxins)

Aerobic, endospore-forming, Aerobic, endospore-forming, Reservoir – Contaminated animals (herbivores) Reservoir – Contaminated animals (herbivores)

and animal productsand animal products Transmission and DevelopmentTransmission and Development

Cutaneous anthrax – through a cut in the skinCutaneous anthrax – through a cut in the skin Figure 25-3, page 268Figure 25-3, page 268 20% mortality w/o treatment, less than 1% with 20% mortality w/o treatment, less than 1% with

Gastrointestinal anthrax – rare (~100% mortality)Gastrointestinal anthrax – rare (~100% mortality)

Disease of the DayDisease of the Day Inhalational or Pulmonary anthrax – endospores Inhalational or Pulmonary anthrax – endospores

inhaledinhaled Can show 2 or more months of latencyCan show 2 or more months of latency Days 1-2 mild fever, cough, chest pain (non-specific)Days 1-2 mild fever, cough, chest pain (non-specific) Death usually occurs within 3 days w/o treatmentDeath usually occurs within 3 days w/o treatment Almost 100% mortalityAlmost 100% mortality

Lab ID: microscopy and specific antigen Lab ID: microscopy and specific antigen detectiondetection

Prevention and Control Prevention and Control vaccine (6 initial + yearly booster) vaccine (6 initial + yearly booster) antibiotics effective if given in timeantibiotics effective if given in time

Cell Structure ReviewCell Structure Review Find a partner and review the structure of Find a partner and review the structure of

bacterial cellsbacterial cells

EndosymbiosisEndosymbiosis The Theory of EndosymbiosisThe Theory of Endosymbiosis Supporting Evidence:Supporting Evidence:

Mitochondrial DNAMitochondrial DNA 70S ribosomes70S ribosomes Binary FissionBinary Fission RNA sequencingRNA sequencing