Ch 4
Functional anatomy of Bacteria
and other Microbes
Or
The differences between
Eukaryotic and Prokaryotic
cells
Q&A
• Penicillin was
called a “miracle
drug” because it
doesn’t harm
human cells.
Why doesn’t it?
• Proks and euks are
similar in chemical
composition and
reaction
• Proks lack membrane
bound organelles
• Only Proks have
peptidoglycan
• Euks have membrane
bound organelles
• Euks have paired
chromosomes
• Euks have histones
Nick sees the difference mainly
in information and structural
capacity
• Proks lack membrane-enclosed
organelles
• Euks are like a 2mhz 100gb home
computer
• Proks are like a calculator
• Human genome 4x109
• E. coli 4x106
The prokaryote
• Unicellular
• Multiply by binary fission
• Differentiated by
–
–
–
–
–
–
Morphology
Chemical composition
Nutritional requirements
Biochemical activates
Sources of energy
Other tests
Size
• 0.2 to 2um in diameter
• 2-8um in length
• In biological systems there are always
exceptions these are general sizes.
Shape
Shape
• Coccus
– Diplococci
– Streptococci
– Staphylococci
• Bacillus
• Spiral
• Other pleomorphic
shapes
Basic components of a
bacterial cell fig 4.6
Parts not seen
• Glycocalyx
– Capsule
– Slime layer
– Extracellular
polysaccharide
• Function
• Toxicity
• Protect from
phagocytosis
• Allow adherence
• Reduce water loss
• Collect nutrients
Flagella:
long filamentous appendages with filament,
hook and basal body
• Used in movement
• Can present taxis
– Negative
– Positive
• Monotrichous
• Peritrichous
• Flagellar H protein
acts as an antigen
E.c O157:H7
• Flagellin
Flagella Arrangement
Figure 4.7
Fimbriae/pili
• Shorter and less
complex than flagella
• Helps adhere to
surfaces
• Used for sex and
communication
Cell wall
• Major difference between eukaryotic and prok orgs.
• Surrounds plasma membrane provides protection
• Peptidoglycan
– Polymer of
• NAG
• NAM
• Short amino acid chain
• Production inhibited by antibiotics
• Prevents osmotic damage
• Damage to cw is almost always lethal except
Gram Positives have large cell
wall and Teichoic acids
Gram neg have
lipopolysaccharide
Peptidoglycan
• Polymer of
disaccharide:
– Nacetylglucosamine
(NAG)
– N-acetylmuramic
acid (NAM)
Figure 4.12
Peptidoglycan in Gram-Positive
Bacteria
Figure 4.13a
The Cell Wall
• Prevents osmotic lysis
• 4-7
Differentiate protoplast,
spheroplast, and L form.
• Made of peptidoglycan (in bacteria)
• Linked by polypeptides
Figure 4.6
Gram-Positive Bacterial Cell Wall
Figure 4.13b
Gram-Negative Bacterial Cell
Wall
Figure 4.13c
Gram-positive Gram-positive
Cell Wall
Cell Wall
 Thin peptidoglycan
• Thick peptidoglycan  Outer membrane
• Teichoic acids
 Periplasmic space
Figure 4.13b–c
Gram neg
• Lipoprotein phospholipid outer membrane
surrounding a thin peptidoglycan
• Makes gram neg resistant to
– Phagocytosis
– Antibiotics
– Chemical reactions
– Enzymes (lysozyme)
– Has lipid A endotoxin
– O polysaccaride antigen O157:H7 E.c.
Gram-Negative Outer
Membrane
Figure 4.13c
How the gram stain works to
differentiate between G+ and G-
The Gram Stain
(a) Gram-Positive
(b) Gram-Negative
Table 4.1
The 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
Gram-Positive Gram-Negative
Cell Wall
Cell Wall
 4-ring basal body
• 2-ring basal body
• Disrupted by
lysozyme
• Penicillin sensitive
 Endotoxin
 Tetracycline sensitive
Figure 4.13b–c
Nontypical cell walls
• Mycoplasma (acid fast) do not have ppt
containing cell wall.
• Archaea contain another chemical called
pseudomurein
Atypical Cell Walls
• Acid-fast cell walls
– Like gram-positive
– Waxy lipid (mycolic acid) bound to
peptidoglycan
– Mycobacterium
– Nocardia
Figure 24.8
Atypical Cell Walls
• Mycoplasmas
– Lack cell walls
– Sterols in plasma membrane
• Archaea
– Wall-less or
– Walls of pseudomurein (lack NAM and D-amino
acids)
Damage to the Cell Wall
•
•
•
•
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
– Protoplasts and spheroplasts are susceptible to
osmotic lysis
• L forms are wall-less cells that swell into irregular
shapes
Plasma membrane
• Defines the living and nonliving parts of
the cell
– Everything on the inside is living
– Everything on the outside is not living
• Is selectively permeable
• Workspace for enzymes of metabolic
reactions
•
•
•
•
Plasma Membrane
Phospholipid bilayer
Peripheral proteins
Integral proteins
Transmembrane proteins
Figure 4.14b
PM Workspace
– Nutrient breakdown
– Energy production
– Photosynthesis
– Afforded by mesosomes which are regular
infoldings of the plasma membrane
• Weaknesses: destroyed by actions of
alcohols, detergents and polymyxins
Fluid Mosaic Model
• Membrane is as
viscous as olive oil.
• Proteins move to
function
• Phospholipids rotate
and move laterally
Figure 4.14b
Plasma Membrane
• Damage to the membrane by alcohols,
quaternary ammonium (detergents) and
polymyxin antibiotics causes leakage of
cell contents.
Movement of Materials across
Membranes
• Simple diffusion:
Movement of a
solute from an
area of high
concentration to
an area of low
concentration
Figure 4.17a
Movement of Materials across
Membranes
• Facilitated diffusion: Solute combines
with a transporter protein in the membrane
Figure 4.17b-c
Movement of Materials across
Membranes
ANIMATION Passive Transport: Special Types of Diffusion
ANIMATION Passive Transport: Principles of Diffusion
Movement of Materials across
Membranes
• Osmosis: The
movement of water
across a selectively
permeable membrane
from an area of high
water to an area of
lower water
concentration
• Osmotic pressure:
The pressure needed
to stop the movement
of water across the
membrane
Figure 4.18a
Movement of Materials across
Membranes
• Through lipid layer
• Aquaporins (water
channels)
Figure 4.17d
The Principle of Osmosis
Figure 4.18a–b
The Principle of Osmosis
Figure 4.18c–e
Movement of Materials across
Membranes
• Active transport: Requires a transporter
protein and ATP
• Group translocation: Requires a
transporter protein and PEP
ANIMATION Active Transport: Types
ANIMATION Active Transport: Overview
Cytoplasm's
• The liquid component of the cell within the
PM
• Mostly water, dissolved ions, DNA
ribosomes and inclusions
• Concept of homeostasis
Nuclear area
• Contains the bacterial chromosome
• Bacteria may also have plasmids with up
to 25% of the genetic materials
Ribosomes
Figure 4.6a
Ribosomes
Figure 4.19
Inclusions
• Typically reserve deposits of excess
materials like inorganic phosphate
• Polysaccharide granules
• Lipids
• Sulfur
• Gas
• iron
The Prokaryotic Ribosome
• Protein synthesis
• 70S
– 50S + 30S subunits
Figure 4.19
Magnetosomes
Figure 4.20
Inclusions
• Metachromatic
granules (volutin)
• Polysaccharide
granules
• Lipid inclusions
• Sulfur granules
• Carboxysomes
• Gas vacuoles
• Magnetosomes
• Phosphate reserves
•
•
•
•
Energy reserves
Energy reserves
Energy reserves
Ribulose 1,5-diphosphate
carboxylase for CO2
fixation
• Protein-covered cylinders
• Iron oxide
(destroys H2O2)
Endospores
• Resting and waiting
stage
• Resistant to drying
and other harsh
conditions
The Eukaryotic cell
Comparison
•
•
•
•
Flagella and cilia tubulin (9/2) arrangement
Cell wall of different materials
Glycocalyx
Plasma membrane
organelles
•
•
•
•
•
•
•
•
•
Nucleus
ER
80s ribosomes
Golgi complex
Lysozymes
Vacuoles
Mitochondria
Chloroplasts
Peroxisomes
Organelles
•
•
4-18 Define organelle.
4-19 Describe the functions of the
nucleus, endoplasmic reticulum, Golgi
complex, lysosomes, vacuoles,
mitochondria, chloroplasts, peroxisomes,
and centrosomes.
Organelles
• Nucleus: Contains chromosomes
• ER: Transport network
• Golgi complex: Membrane formation and
secretion
• Lysosome: Digestive enzymes
• Vacuole: Brings food into cells and
provides support
Organelles
• Mitochondrion: Cellular respiration
• Chloroplast: Photosynthesis
• Peroxisome: Oxidation of fatty acids;
destroys H2O2
• Centrosome: Consists of protein fibers and
centrioles
The Eukaryotic Nucleus
Figure 4.24
The Eukaryotic Nucleus
Figure 4.24a–b
Rough Endoplasmic Reticulum
Figure 4.25
Detailed Drawing of
Endoplasmic Reticulum
Figure 4.25a
Micrograph of Endoplasmic
Reticulum
Figure 4.25b
Golgi Complex
Figure 4.26
Lysosomes and Vacuoles
Figure 4.22b
Mitochondria
Figure 4.27
Chloroplasts
Figure 4.28
Chloroplasts
Figure 4.28a
Chloroplasts
Figure 4.28b
Peroxisome and Centrosome
Figure 4.22b
Eukaryotic Cell
• Not membrane-bound:
– Ribosome
– Centrosome
and
– Centriole
Protein synthesis
Consists of protein fibers
centrioles
Mitotic spindle formation
Evolution of eukaryotes
• Endosymbiotic theory
Membrane activity
•
•
•
•
•
•
Diffusion
Osmosis
Passive diffusion
Facilitated diffusion
Active transport
Know the relationships
Movement Across Membranes
• Active transport of substances requires a
transporter protein and ATP.
• Group translocation of substances
requires a transporter protein and PEP.