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TORTORA • FUNKE
• CASE
Microbiology
AN INTRODUCTION
EIGHTH EDITION
B.E Pruitt & Jane J. Stein
Chapter 4
Functional Anatomy of Prokaryotic and
Eukaryotic Cells
PowerPoint® Lecture Slide Presentation prepared by Christine L. Case
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Prokaryotic Cells
Learning objective: compare and contrast overall cell structure of
prokaryotes and eukaryotes.
• 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
• Cell membrane
• Cell membrane
• Cytoplasm
• Cytoplasm
• 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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Learning objective: Identify the three basic shapes of bacteria.
• Average size: 0.2 -1.0 µm  2 - 8 µm (1 x 10-6 m)
• Are unicellular and most multiply by binary fission
• Basic shapes:
COCCUS
BACILLUS
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SPIRAL
Arrangements
• Pairs: diplococci,
diplobacilli
• Clusters:
staphylococci
• Chains:
streptococci,
streptobacilli
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Arrangements
of cocci:
Can be
determined by
division of
planes.
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Arrangements
of bacilli:
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Arrangements
of spiral
bacteria:
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Doublestranded helix
formed by
Bacillus
subtilis.
Bacillus cells
often remain
attached to
each other,
forming
extended
chains.
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• Unusual shapes (Prokaryotes)
• Star-shaped Stella
• Square Haloarcula (halophilic archaea – salt-loving)
• Most bacteria are monomorphic (single shape)
• A few are pleomorphic (many shapes)
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Figure 4.5
Learning objective: Describe the structure and function of the
glycocalyx, flagella, axial filaments, fimbriae, and pili.
Prokaryote cell
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Glycocalyx
• Outside cell wall
• Usually sticky
• A capsule is neatly
organized
• A slime layer is
unorganized & loose
glycocalyx
• Extracellular
polysaccharide (EPS)
allows cell to attach
• Capsules prevent
phagocytosis
• Protects against
dehydration or loss of
nutrients.
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Figure 4.6a, b
Flagella
• Long filamentous
appendages of a
filament, hook, and
basal body
• 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
Four arrangements of flagella:
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Figure 4.7
Motile Cells
• Rotate flagella to run or tumble
• Move toward or away from stimuli (positive and
negative taxis)
• Flagella H proteins are antigens
(e.g., E. coli O157:H7)
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Motile Cells
A Proteus cell swarming
may have 1000+
peritrichous flagella.
(from all sides)
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Figure 4.9
Axial Filaments (endoflagellum)
• Endoflagella
• In spirochetes
• Anchored at one end
of a cell
• Rotation causes cell
to move
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Figure 4.10a
Fimbriae and Pili
• Are short, thin
appendages
• Fimbriae of this E. Coli
cell allow attachment
(velcro). Cell is
beginning to divide.
• Pili are used to transfer
DNA from one cell to
another
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Figure 4.11
Learning objectives: Compare/contrast cell walls of gram-positive
bacteria, gram-negative bacteria, archaea, and mycoplasmas.
Differentiate between protoplast, spheroplast, and L form.
Cell Wall
• Prevents osmotic lysis (protects against changes in water pressure)
• Made of peptidoglycan (in bacteria = NAG+NAM+amino acids) –
penicillin interferes with production of peptidoglycan
• Contributes to disease capability and 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
The small arrows denote where
(NAM)
• Linked by polypeptides
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penicillin interferes with linkage of
peptidoglycan rows.
Figure 4.13a
Gram positive vs. gram negative cell walls
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Figure 4.13b, c
Gram-positive cell walls
• Thick peptidoglycan
• Teichoic acids
(alcohol+phosphate)
• In acid-fast cells,
contains mycolic
acid (waxy lipid) –
allows them to be
grouped into
medically significant
types.
Gram-negative cell walls
• Thin peptidoglycan (subject
to mechanical breakage)
• No teichoic acids
• Outer membrane:
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• Evades phagocytosis
• Barrier to certain antibiotics
Gram-Positive cell walls
• Teichoic acids:
• Lipoteichoic acid links to plasma membrane
• Wall teichoic acid links to peptidoglycan
• May regulate movement of cations (+ charge)
• Polysaccharides provide antigenic variation
(identification)
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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 (30+ liver
proteins that protect host), antibiotics.
• O polysaccharide antigen, e.g., E. coli O157:H7.
• Lipid A is an endotoxin.
• Porins (proteins) form channels through membrane to
pass other molecules
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Gram-Negative Outer Membrane
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Figure 4.13c
Gram Stain Mechanism
• Crystal violet-iodine (CV-I) crystals form in cell
combining with peptidoglycan
• 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 (Genus)
• Lack cell walls
• Sterols in plasma membrane
• Archaea
• Wall-less, or
• Walls of pseudomurein (lack NAM and D amino
acids, peptidoglycan)
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Damage to Cell Walls
• Lysozyme digests disaccharide in peptidoglycan
(gram+ cell walls destroyed, gram- damaged, resulting
in spheroplast).
• Spheroplast is a wall-less Gram-positive cell.
• Penicillin inhibits peptide bridges in peptidoglycan.
• Protoplast is a wall-less cell.
• L forms are wall-less cells that swell into irregular
shapes (gram+ and -).
• Protoplasts and spheroplasts are susceptible to
osmotic lysis.
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Plasma (cytoplasmic) Membrane
Learning objectives: Describe the structure, chemistry, and functions
of prokaryotic plasma membrane.
Define simple diffusion, facilitated diffusion, osmosis, active
transport, and group translocation.
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Figure 4.14a
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Plasma Membrane – Fluid Mosaic Model
• Selectively permeable
• 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
Plasma Membrane
• Carry enzymes for metabolic reactions: nutrient
breakdown, energy production, photosynthesis
• Selective permeability allows passage of some
molecules
• Enzymes for ATP production
• Photosynthetic pigments on foldings called
chromatophores or thylakoids
• Damage to the membrane by alcohols, quaternary
ammonium (detergents) and polymyxin antibiotics
causes leakage of cell contents.
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Movement Across Membranes
• High to low concentration:
• Movement may be passive (no energy expenditure –
diffusion or facilitated diffusion):
• Simple diffusion: Movement of a solute from an area
of high concentration to an area of low concentration.
(ions move until equilibrium reached)
• Facilitative diffusion: Solute combines with a
transporter protein in the membrane.
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Movement Across Membranes
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Figure 4.17
Movement Across Membranes
• Osmosis (always involves
water):
• Movement of water
across a selectively
permeable membrane
from an area of high
water concentration to
an area of lower water.
• Osmotic pressure
• The pressure needed to
stop the movement of
water across the
membrane.
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Figure 4.18a
Osmosis
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Figure 4.18c-e
Movement Across Membranes
• Low to high concentration (against gradient) – cell
must expend energy:
• Active transport of substances requires a transporter
protein and ATP.
• Group translocation of substances requires a
transporter protein and PEP. (phospheonolpyruvic
acid)
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Cytoplasm
• Cytoplasm is the fluid substance inside the plasma
membrane (water, inorganic and organic molecules,
DNA, ribosomes, and inclusions)
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Figure 4.6a, b
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Nuclear Area
Learning objectives: Identify functions of the nuclear area,
ribosomes, and inclusions.
• Nuclear area (nucleoid) – contains single long,
continuous, double-stranded DNA called bacterial
chromosome.
• Bacteria can contain plasmids – circular DNA
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Figure 4.6a, b
Ribosomes = rRNA + proteins
Sites of protein synthesis (rRNA) – free floating, not tied to
endoplasmic reticulum as in eukaryotes.
Figure 4.6a
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Ribosomes
The letter S refers to Svedberg units = relative
rate of sedimentation.
Because of differences in prokaryotic and
eukaryotic ribosomes, the microbe can be killed
by antibiotics while eukaryotic host cell is
unaffected.
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Figure 4.19
Inclusions
FUNCTION
• Metachromatic granules
(volutin)
•Phosphate reserves
• Polysaccharide granules
•Energy reserves
• Lipid inclusions
•Energy reserves
• Sulfur granules
•Energy reserves
• Carboxysomes
•Ribulose 1,5diphosphate carboxylase
for CO2 fixation
• Gas vacuoles
•Protein covered cylinders
• Magnetosomes
•Iron oxide
(destroys H2O2)
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Iron-oxide inclusions in some gram-negative
bacteria that act like magnets.
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Endospores
Learning objective: Describe the functions of endospores,
sporulation, and endospore germination.
• Resting cells formed for survival
• Sporulation: Endospore formation
• Resistant to desiccation, heat, chemicals
• Bacillus, Clostridium
• Germination: Return to vegetative state
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Endospores tend to
form under conditions
of stress.
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Eukaryotic 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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Eukaryotic Flagella and Cilia
Prokaryotic
flagella rotate,
eukaryotic
flagella wave
Euglena (evolutionary
building block)
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Flagella and Cilia
• Flagella are few and long (motility), cilia are
numerous and short (motility and move
substances along cell surface)
• Microtubules
• Tubulin
• 9 pairs + 2 arrangements
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Figure 4.23c
Cell Wall and Glycocalyx
Learning objective: Compare and contrast prokaryotic and
eukaryotic cell walls and glycocalyxes.
• Cell wall
• Plants, algae, some fungi contain cellulose
• Carbohydrates
• Cellulose, chitin (fungal), glucan & mannan (yeast)
• Glycocalyx surround animal cells (strength, attachment
to other cells)
• Carbohydrates extending from animal plasma
membrane
• Bonded to proteins and lipids in membrane
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Plasma Membrane
Learning objective: Compare and contrast prokaryotic and
eukaryotic plasma membranes.
• Phospholipid bilayer in both p. and e. cells
• Peripheral proteins
• Integral proteins
• Transmembrane proteins
• Sterols
• Glycocalyx carbohydrates not found in p. cells except
Mycoplasma bacteria
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Plasma Membrane
• Selective permeability allows passage of some
molecules
• Simple diffusion
• Facilitative diffusion
• Osmosis
• Active transport
• Endocytosis
• Phagocytosis: Pseudopods extend and engulf
particles (solids)
• Pinocytosis: Membrane folds inward bringing in fluid
and dissolved substances (liquids)
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Eukaryotic Cell
• Cytoplasm
membrane
Substance inside plasma
and outside nucleus
• Cytosol
Fluid portion of cytoplasm
• Cytoskeleton
Microfilaments,
intermediate filaments,
microtubules
• Cytoplasmic streaming
Movement of cytoplasm
throughout cells
Learning objectives:
Define organelle.
Describe the functions of the nucleus, endoplasmic reticulum,
ribosomes, Golgi complex, lysosomes, vacuoles, mitochondria,
chloroplasts, peroxisomes, and centrosomes.
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Organelles
• Specialized membrane-bound structure in cytoplasm:
• Nucleus
Contains chromosomes (DNA)
• ER
Transport network, ribosomes
• Golgi complex
Membrane formation and protein
secretion
• Lysosome
Digestive enzymes
• Vacuole
Brings food into cells and
provides support
• Mitochondrion
Cellular respiration (ATP)
• Chloroplast
Photosynthesis (70S ribosomes)
• Peroxisome
Oxidation of fatty acids;
destroys H2O2
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Eukaryotic Cell
• Not membrane-bound:
• Ribosome
Protein synthesis (translation)
• Centrosome
Consists of protein fibers and
centrioles
• Centriole
Mitotic spindle formation
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Eukaryotic Nucleus
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Figure 4.24
Endoplasmic Reticulum
Rough ER contains
ribosomes – site of protein
translation
Smooth ER performs various
functions:
•Synthesizes phospholipids,
fats, steroids
•In liver: glucose release
and detoxify toxins
•Creates vesicles
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Figure 4.25
Ribosomes
• 80S
• Membrane-bound
Attached to ER
• Free
In cytoplasm
• 70S
• In chloroplasts and mitochondria
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Golgi Complex
Golgi complex modifies, sorts, and packages proteins received from
the ER; discharges proteins via exocytosis; replaces portions of the
plasma membrane; and forms lysosomes (digestive enzymes).
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Figure 4.26
Lysosomes (digestive enzymes)
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Figure 4.22b
Vacuoles (storage of toxins, food, water)
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Figure 4.22b
Mitochondrion (furnace of the cell)
Site of the
Krebs Cycle,
which produces
the energy
currency of the
cell - ATP
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Figure 4.27
Chloroplast
Structure similar to mitochondria – the
reverse side of respiration:
C6H12O6 + O2 = H2O + CO2 + ATP
Photosynthesis:
H2O + CO2 + sun = C6H12O6 + O2
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Figure 4.28
Endosymbiotic Theory
Learning objective:
Discuss evidence that
supports the
endosymbiotic theory of
eukaryotic evolution.
•Mitochondria and
chloroplasts resemble
bacteria in size and
shape as do their
ribosomes
•These organelles
contain circular DNA
like prokaryotes and can
reproduce apart from
their host cell
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Figure 10.2