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TORTORA • FUNKE
• CASE
Microbiology
AN INTRODUCTION
EIGHTH EDITION
B.E Pruitt & Jane J. Stein
Chapter 4, part A
Functional Anatomy of Prokaryotic and
Eukaryotic Cells
PowerPoint® Lecture Slide Presentation prepared by Christine L. Case
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
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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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
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
(Treponema
pallidum)
• Anchored at one end
of a cell
• Rotation causes cell
to move
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Figure 4.10a
• Fimbriae in many G-ve
bacteria
• Shorter, straighter, and
thinner than flagella
• Few to several hundred
• For attachment rather
than for motility
• Pili are used to transfer
DNA from one cell to
another (sex pili)
• One or two per cell
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Figure 4.11
Cell Wall
• Prevents osmotic lysis
• Made of peptidoglycan (in bacteria)
• Contribute to the ability of some species to cause disease
• Site of action of some antibiotics
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Figure 4.6a, b
Peptidoglycan (murein)
• Polymer of disaccharide N-acetylglucosamine (NAG)
& N-acetylmuramic acid (NAM)
• Linked by polypeptides (4 amino acids in alternating
pattern of D and L forms)
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Figure 4.13a
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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 (waxy lipid)
• Outer membrane
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Gram-Positive cell walls
• Teichoic acids:
• Lipoteichoic acid links to plasma membrane
• Wall teichoic acid links to peptidoglycan
• Alcohol (such as glycerol or ribitol) and phosphate
• May regulate movement of cations
• Polysaccharides provide antigenic variation
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Figure 4.13b
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 (as teichoic acid in G+ve),
e.g., E. coli O157:H7.
• Lipid A is an endotoxin (toxic; fever).
• Porins (proteins) form channels through membrane
(passage of nucleotides, disaccharides, peptides,
amino acids, vitamine B12, and iron )
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Gram-Negative Outer Membrane
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Figure 4.13c
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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Atypical Cell Walls
• Mycoplasmas
• Lack cell walls
• Sterols in plasma membrane (protect them from
osmotic lysis)
• Archaea
• Wall-less, or
• Walls of pseudomurein (lack NAM and D amino
acids)
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Damage to Cell Walls
• Lysozyme (constituent of tears, mucus, and saliva)
digests disaccharide in peptidoglycan.
• Penicillin inhibits peptide bridges in peptidoglycan.
• Protoplast is a wall-less cell.
• Spheroplast is a wall-less Gram-negative cell.
• L forms are wall-less cells that swell into irregular
shapes.
• Protoplasts and spheroplasts are susceptible to
osmotic lysis.
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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