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TORTORA • FUNKE
• CASE
Microbiology
AN INTRODUCTION
EIGHTH EDITION
B.E Pruitt & Jane J. Stein
Functional Anatomy of Prokaryotic and
Eukaryotic Cells
PowerPoint® Lecture Slide Presentation prepared by Christine L. Case
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Size Comparisons of Selected Microorganisms/Parasites
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Prions and Viroids
• Prions are proteins that are believed to cause
diseases like BSE.
• Viroids are small RNA’s with no associated
protein that causes diseases in plants.
• Neither fit the criteria for living organisms, but
they are microbes and are therefore studied by
microbiologists.
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Viruses
• Consist of nucleic acid and protein.
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Viruses 2
• Obligate intracellular parasites.
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Viruses 3
• Are they really alive?
• In general, are smaller than most prokaryotes.
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Viruses 4
• Reproduce using host cell mechanisms.
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Viruses 4
• Adenovirus
Copyright notice: This notice must accompany any copy of the images. The images must not
be used for commercial purposes without the consent of the copyright owners. The images
are not in the public domain. The images can be freely used for educational purposes.
Copyright 1994 Veterinary Sciences Division.
• Rhinovirus
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Prokaryotic Cells
• Comparing Prokaryotic and Eukaryotic Cells
• Prokaryote comes from the Greek words for
prenucleus.
• Eukaryote comes from the Greek words for
true nucleus.
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Prokaryote
Eukaryote
• One circular
chromosome, not in
a membrane
• Paired
chromosomes, in
nuclear membrane
• No histones
• Histones
• No organelles
• Organelles
• Peptidoglycan cell
walls
• Polysaccharide cell
walls
• Binary fission
• Mitotic spindle
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• Average size: 0.2 -1.0 µm  2 - 8 µm
• Basic shapes:
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• Unusual shapes
• Star-shaped Stella
• Square Haloarcula
• Most bacteria are monomorphic
• A few are pleomorphic
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Figure 4.5
Arrangements
• Pairs: diplococci,
diplobacilli
• Clusters:
staphylococci
• Chains:
streptococci,
streptobacilli
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Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
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Glycocalyx
• Outside cell wall
• Usually sticky
• A capsule is neatly
organized
• A slime layer is
unorganized & loose
• Extracellular
polysaccharide
allows cell to attach
• Capsules prevent
phagocytosis
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Figure 4.6a, b
Flagella
• Outside cell wall
• Made of chains of
flagellin
• Attached to a protein
hook
• Anchored to the wall
and membrane by
the basal body
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Figure 4.8
Flagella Arrangement
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Figure 4.7
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Figure 4.8
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Motile Cells
• Rotate flagella to run or tumble
• Move toward or away from stimuli (taxis)
• Flagella proteins are H antigens
(e.g., E. coli O157:H7)
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Motile Cells
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Figure 4.9
Axial Filaments
• Endoflagella
• In spirochetes
• Anchored at one end
of a cell
• Rotation causes cell
to move
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Figure 4.10a
• Fimbriae allow
attachment
• Pili are used to
transfer DNA from
one cell to another
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Figure 4.11
Pili
• Short protein appendages
• smaller than flagella
• Adhere bacteria to surfaces
• E. coli has numerous types
• K88, K99, F41, etc.
• Antibodies to will block adherance
• F-pilus; used in conjugation
• Exchange of genetic information
• Flotation; increase boyancy
• Pellicle (scum on water)
• More oxygen on surface
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F-Pilus for Conjugation
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Cell Wall
• Prevents osmotic lysis
• Made of peptidoglycan (in bacteria)
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Figure 4.6a, b
Peptidoglycan
• Polymer of disaccharide
N-acetylglucosamine (NAG) & N-acetylmuramic acid
(NAM)
• Linked by polypeptides
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Figure 4.13a
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Gram-Positive cell walls
• Teichoic acids:
• Lipoteichoic acid links to plasma membrane
• Wall teichoic acid links to peptidoglycan
• May regulate movement of cations
• Polysaccharides provide antigenic variation
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Figure 4.13b
Teichoic Acids
• Gram + only
• Glycerol, Phosphates, & Ribitol
• Attachment for Phages
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Figure 4.13b, c
Gram-positive cell walls
Gram-negative cell walls
• Thick peptidoglycan
• Thin peptidoglycan
• Teichoic acids
• No teichoic acids
• In acid-fast cells,
contains mycolic
acid
• Outer membrane
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Gram-Negative Outer Membrane
• Lipopolysaccharides, lipoproteins, phospholipids.
• Forms the periplasm between the outer membrane and
the plasma membrane.
• Protection from phagocytes, complement, antibiotics.
• O polysaccharide antigen, e.g., E. coli O157:H7.
• Lipid A is an endotoxin.
• Porins (proteins) form channels through membrane
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Gram-Negative Outer Membrane
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Figure 4.13c
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Lipopolysaccharide (LPS)
• Endotoxin or Pyrogen
• Fever causing
• Toxin nomenclature
• Endo- part of bacteria
• Exo- excreted into environment
• Structure
• Lipid A
• Polysaccharide
• O Antigen of E. coli, Salmonella
• G- bacteria only
• Alcohol/Acetone removes
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LPS (cont’d)
• Functions
• Toxic; kills mice, pigs, humans
• G- septicemia; death due to LPS
• Pyrogen; causes fever
• DPT vaccination always causes fevers
• Adjuvant; stimulates immunity
• Heat Resistant; hard to remove
• Detection (all topical & IV products)
• Rabbits (measure fever)
• Amoebocytes Lyse in presence of LPS
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LPS (cont’d.)
• Appearance of Colonies
• Mucoid = Smooth (lots of LPS or capsule)
• Dry = Rough (little LPS or capsule)
• O Antigen of Salmonella and E. coli
• 2,000 different O Ags of Salmonella
• 100’s different O Ags of E. coli
• E. coli O157
• O Ags differ in Sugars, not Lipid A
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Damage to Cell Walls
• Lysozyme digests disaccharide in peptidoglycan.
• Penicillin inhibits peptide bridges in peptidoglycan.
• Protoplast is a wall-less cell.
• Spheroplast is a wall-less Gram-positive cell.
• L forms are wall-less cells that swell into irregular
shapes.
• Protoplasts and spheroplasts are susceptible to
osmotic lysis.
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Gram Stain Mechanism
• Crystal violet-iodine crystals form in cell
• Gram-positive
• Alcohol dehydrates peptidoglycan
• CV-I crystals do not leave
• Gram-negative
• Alcohol dissolves outer membrane and leaves holes
in peptidoglycan
• CV-I washes out
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Bacterial Stains
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Plasma Membrane
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Figure 4.14a
Plasma Membrane
• Phospholipid bilayer
• Peripheral proteins
• Integral proteins
• Transmembrane proteins
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Figure 4.14b
Fluid Mosaic Model
• Membrane is as viscous
as olive oil.
• Proteins move to function
• Phospholipids rotate and
move laterally
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Figure 4.14b
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Cytoplasm
• 80% Water {20% Salts-Proteins)
• Osmotic Shock important
• DNA is circular, Haploid
• Advantages of 1N DNA over 2N DNA
• More efficient; grows quicker
• Mutations allow adaptation to environment quicker
• Plasmids; extra circular DNA
• Antibiotic Resistance
• No organelles (Mitochondria, Golgi, etc.)
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Spores
SPORE
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Cross-section of Bacillus spore
The central protoplast, or germ cell, carries the constituents of the future
vegetative cell, accompanied by dipicolinic acid --heat resistance of the spore.
Surrounding the protoplast is a cortex consisting largely of peptidoglycan
(murein), -- heat and radiation resistance of the spore.
The inner layer, the cortical membrane or protoplast wall, becomes the cell
wall of the new vegetative cell when the spore germinates.
The spore coats, which constitute up to 50 percent of the volume of the spore,
protect it from chemicals, enzymes, etc.
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The developmental cycle of the Endospore.
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Bacterial endospores. Phase microscopy of sporulating bacteria
demonstrates the refractility of endospores, as well as
characteristic spore shapes and locations within the mother cell.
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Atypical Cell Walls
• Mycoplasmas
• Lack cell walls
• Sterols in plasma membrane
• Archaea
• Wall-less, or
• Walls of pseudomurein (lack NAM and D amino
acids)
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Archaebacteria
• Newly added taxonomic kingdom.
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Archeabacteria 2
• Single celled prokaryotes.
• Extremophiles.
• 4 broad groups.
• Methanogens + extreme halophiles
• Methanogens only
• Sulfur dependent
• Thermophiles
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Archeabacteria 3
The preceding Methanobacterim image is from the Department of Microbiology and
Evolutionary Biology at the University of Nijmegen, the Netherlands.
http://www-micrbiol.sci.kun.nl/micrbiol/micrgala.html
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Eukaryote Cell Structure
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Algae
• Eukaryotes that may be unicellular,
colonial or filamentous.
These images are from the Molecular Evolution and Organelle Genomics program at the University of Montreal.
Copyright 1994-1997 by Charles J. O’Kelly and Tim Littlejohn. Distribution for noncommercial purposes permitted
so long as this copyright notice is included and acknowledgement is made.
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Algae
2
• Aquatic or terrestrial.
• Mostly plant-like characteristics.
• Photosynthetic.
• Great variety of types, but all contain chlorophyll.
• Some animal-like characteristics like
phagocitosis of other organisms.
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Algae 3
• Important marine food source.
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Protozoa
• Single celled eukaryotes, but may form
colonial aggregates.
• Aquatic with animal-like characteristics.
This image is from the Molecular Evolution and Organelle
Genomics program at
the University of Montreal. Copyright 19941997 by Charles J. O’Kelly and Tim
Littlejohn. Distribution for
noncommercial purposes permitted so long as this
copyright notice is
included and acknowledgement is made.
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Protozoa 2
• Ingest organic matter for nutrients.
• Vary greatly in size from 0.003mm to 5mm.
• Many are human parasites.
• Most are motile.
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Fungi
• Very diverse group of eukaryotes.
• Not all are microbes.
• Yeasts are unicellular and spherical.
• Molds are filamentous with branching.
The preceding Pyromyces sp. image is from the Department of Microbiology
and Evolutionary Biology at the University of Nijmegen, the Netherlands.
http://wwwmicrbiol.sci.kun.nl/micrbiol/micrgala.html
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Fungi 2
• Non-photosynthetic.
• Require the uptake of organic matter
for nutrients.
• Saprophytic or parasitic.
• Propagate by spores.
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