Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings M I C R O B I O L O G Y 4 Dr Mila Nu Nu Htay Bacterial Anatomy, Physiology and Growth (Part 1)
Dec 24, 2015
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
PowerPoint® Lecture Slide Presentation prepared by Christine L. Case
M I C R O B I O L O G Y a n i n t r o d u c t i o n
ninth edition TORTORA FUNKE CASE
Part A 4
Dr Mila Nu Nu Htay
Bacterial Anatomy,
Physiology and Growth
(Part 1)
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Objectives
Size, shape and arrangements of the bacterial cells
Structures of the bacterial cell and their functions
Differences between Gram positive and Gram Negative
cell walls
Gram Stain Mechanism
Physical and chemical requirements for growth
Phases of growth
Measurement of bacterial growth (direct, indirect)
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Comparing prokaryotic and eukaryotic cells
Prokaryote comes from the Greek words for
prenucleus. (eg, bacteria, archaea)
Eukaryote comes from the Greek words for
true nucleus. (eg, algae, fungi, protozoa)
Prokaryotic Cells
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Prokaryote Eukaryote
One circular
chromosome, not in a
membrane
No histones
No organelles
Peptidoglycan cell walls
Binary fission
Paired chromosomes,
in nuclear membrane
Histones
Organelles
Polysaccharide cell walls
Mitotic spindle
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Prokaryotes and eukaryotes
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Size and Shape of the bacterial cells
Average size: 0.2 -2.0 µm (in diameter) 2 - 8 µm (in
length)
Basic shapes
1. Cocci
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Size and Shape of the bacterial cells
2. Bacilli
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Size and Shape of the bacterial cells
3. Spiral bacteria
Spirillum Spirochete
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Size and Shape of the bacterial cells
Unusual shapes
Star-shaped Stella
Square Haloarcula
Most bacteria are monomorphic
A few are pleomorphic
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Arrangements
Pairs: Diplococci,
diplobacilli
Clusters: Staphylococci
Chains: Streptococci,
streptobacilli
Figures 4.1a, 4.1d, 4.2c
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Bacteria
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Glycocalyx
Outside cell wall
Usually sticky
A capsule is neatly organized
A slime layer is unorganized
and loose
Extracellular polysaccharide
allows cell to attach
Capsules prevent phagocytosis
Figure 4.6a–b
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Flagella
Outside cell wall
Three basic parts-
filament, hook, basal
body
Filament attached to a
protein hook
Anchored to the wall
and membrane by the
basal body Figure 4.8a
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Flagella
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Flagella Arrangement
Figure 4.7
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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 – associated with foodborne
epidemics.)
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Motile Cells
Figure 4.9
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Motile Cells
PLAY Animation: Bacterial Motility
Figures 4.9a, 4.23d
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Axial Filaments
Endoflagella or axial filament
In spirochetes
Anchored at one end
of a cell
Rotation causes cell
to move
Figure 4.10a
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Fimbriae and pili
Fimbriae- the hair like
appendages
thinner, shorter and
straighter than the flagella
Allow attachment
Pili
One or two in number
are used to transfer DNA
from one cell to another
Figure 4.11
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Cell Wall
Protect the cell
Prevents osmotic lysis
Made of peptidoglycan (in bacteria)
Site of action of some antibiotics
(eg, penicillin)
Figure 4.6a–b
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Peptidoglycan
Polymer of disaccharide
N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)
Linked by polypeptides
Figure 4.13a
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Gram Positive and Gram Negative cell walls
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Gram-Positive Gram-Negative Cell Walls Cell Walls
Thick peptidoglycan
Teichoic acids
In acid-fast cells,
contains mycolic acid
2 rings in basal body of
flagella
Thin peptidoglycan
No teichoic acids
Outer membrane
4 rings in basal body of
flagella
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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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Gram-Negative Outer Membrane
Lipopolysaccharides, lipoproteins, phospholipids
Forms the periplasm between the outer membrane and
the plasma membrane.
Protection from phagocytes, complement, and
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
Figure 4.13c
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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 (purple color)
Gram-negative
Alcohol dissolves outer membrane and leaves holes
in peptidoglycan.
CV-I washes out
Take safranin stain (pink color)
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Gram Stain
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Gram Stain Procedure
60 seconds
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Gram positive and Gram negative microorganisms
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Atypical Cell Walls
Mycoplasmas
Lack cell walls
Sterols in plasma membrane
Eg, Mycoplasma pneumoniae,
M genitalium.
Archaea
Wall-less or
Walls of pseudomurein (lack NAM and D amino
acids)
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Damage to Cell Walls
Lysozyme (lysosomal enzyme) digests disaccharide in
peptidoglycan.
Penicillin inhibits peptide bridges in peptidoglycan.
Protoplast is a wall-less Gram-positive 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
Figure 4.14a
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Plasma Membrane
Phospholipid bilayer
Peripheral proteins – serves as enzymes
Integral proteins
- Transmembrane proteins
Figure 4.14b
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Fluid Mosaic Model
Membrane is as viscous as olive oil.
Proteins move to function.
Phospholipids rotate
and move laterally.
Figure 4.14b
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Plasma Membrane
Selective permeability allows passage of some
molecules
Enzymes for ATP production
Photosynthetic pigments or chlorophyll are embedded
in the plasma membrane.
Chloroplast
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Plasma Membrane
Damage to the membrane by alcohols, quaternary
ammonium (detergents), and polymyxin antibiotics
causes leakage of cell contents and subsequent cell
death.
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Movement Across Membranes
Simple diffusion: Movement of a solute from an area of
high concentration to an area of low concentration.
(eg, oxygen, carbon dioxide)
Facilitative diffusion: Solute combines with a transporter
protein in the membrane.
(eg, glucose)
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Movement Across Membranes
Figure 4.17
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Movement Across Membranes
Osmosis: The movement of
water across a selectively
permeable membrane from
an area of high water
concentration to an area of
lower water.
Figure 4.18a
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Movement Across Membranes
Figure 4.18a–b
Osmotic pressure:
The pressure
needed to stop the
movement of
water across the
membrane.
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PLAY Animation: Membrane Transport
Movement Across Membranes
Active transport of substances requires a transporter
protein and ATP.
Group translocation - The substance is chemically
altered during transport across the membrane. Once the
substance is altered inside the cell, the plasma membrane is
impermeable to it. So the substance can’t come out of the
cell.
requires a transporter protein and
PEP(phosphoenolpyruvic acid).
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Cytoplasm
Cytoplasm is the substance inside the plasma
membrane.
Figure 4.6a–b
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Nuclear Area
Nuclear area (nucleoid)
The bacterial chromosome is a single, circular, double-
stranded DNA, exists freely in the cytoplasm.
Figure 4.6a–b
Plasmids – Small genetic
elements capable of
independent replication in
bacteria and yeasts or it is an
extrachromosomal genetic
material, replicate
autonomously.
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Ribosomes
Several antibiotics can inhibit the protein synthesis in
the ribosomes.
Figure 4.6a–b
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Ribosomes
Figure 4.19
S – Svedberg Unit
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Inclusions
The cell store the excess nutrients in inclusions and
use them when the nutrient is deficient in environment.
Figure 4.20
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Inclusions
Metachromatic granules
(volutin)
Polysaccharide granules
Lipid inclusions
Sulfur granules
Carboxysomes
Gas vacuoles
Magnetosomes
Phosphate reserves (used in
synthesis of ATP)
Energy reserves
Energy reserves
Energy reserves
Ribulose 1,5-diphosphate
carboxylase for CO2 fixation
Protein covered cylinders
Iron oxide
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Endospores
Resting cells
Resistant to desiccation, heat, chemicals
Bacillus, Clostridium
Sporulation: Endospore formation
Germination: Return to vegetative state
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Endospores
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Endospores of Clostridium tetani