Dr. Alvin Fox

1
Dr. Alvin Fox
2
Key Words
Prokaryotic
Outer membrane
Eubacteria (Bacteria)
Periplasmic space
Oxidative phosphorylation
Eukaryotic
Spheroplast/protoplast
Plasmid
Flagella
Chromosome
Chemotaxis
Ribosome
Axial filament
Peptidoglycan (murein, mucopeptide)
Periplasmic binding protein
Gram stain
Permeases
Gram negative
Storage Granules
Gram positive
Pili (fimbriae)
Cell envelope
Capsule (slime layer, glycocalyx)
Cell membrane
Endospore (spore)
Cell wall
3
PROKARYOTES
EUKARYOTES
BACTERIA
ARCHAEA
4
Prokaryotes (Bacteria)

• Eubacter "True" bacteria
• human pathogens
• clinical or environmental
• one kingdom
• Archaea
• Environmental organisms
• second kingdom

5
Eukaryotes

• Other cell-based life e.g.
• plants
• animals
• fungi

6
Prokaryotic Cell (versus Eukaryotic Cell)

• Not compartmentalized
• Cell membranes lack sterols (e.g. cholesterol)
• Single circular chromosome
• Ribosomes
• - 70S
• - subunits
• 30S (16S rRNA)
• 50S (5S 23S rRNA)

7
Bacteria versus Archaebacteria

• Eubacteria
• peptidoglycan (murein)
• muramic acid
• Archaebacteria
• pseudomurein
• no muramic acid

8
Bacteria versus Archaebacteria

• 16S rRNA
• sequence different

9
Eukaryotic cell
Prokaryotic cell
Gram
(e.g. animal)
Flagellum
Nucleoid
Cell wall
Cell membrane
Rough endoplasmic reticulum
Nucleus
Gram -
Cytoplasm
Mitochondria
10
Bacteria

• Plasmids
• Extra-chromosomal DNA
• multiple copy number
• coding
• - pathogenesis factors
• - antibiotic resistance factors
• bacterial replication

11
The Cell Envelope
Gram Stain
Gram Positive
Gram Negative
12
Oxidative phosphorylation occurs at cell
membrane (since there are no mitochondria).
Cytoplasm
Cell Wall
Cell membrane

• The cell wall is outside of cell membrane
• rigid, protecting cell from osmotic lysis.

13
GRAM POSITIVE
Lipoteichoic acid
Peptidoglycan-teichoic acid
Cytoplasmic membrane
Cytoplasm
GRAM NEGATIVE
Lipopolysaccharide
Porin
Outer Membrane
Braun lipoprotein
Periplasmic space
Inner (cytoplasmic) membrane
Cytoplasm
14
Outer Membrane

• Gram negative bacteria
• major permeability barrier
• space between inner and outer membrane
• periplasmic space
• store degradative enzymes
• Gram positive bacteria
• no periplasmic space

15
GRAM NEGATIVE CELL ENVELOPE
Outer Membrane (Major permeability barrier)
Lipopolysaccharide
Porin
Braun lipoprotein
Periplasmic space
Degradative enzyme
Periplasmic binding protein
Permease
Inner (cytoplasmic) membrane
Cytoplasm
16
GRAM POSITIVE CELL ENVELOPE
Degradative enzyme
Peptidoglycan-teichoic acid
Lipoteichoic acid
Cytoplasmic membrane
Cytoplasm
17
FLAGELLA

• Some bacteria are motile
• Locomotory organelles- flagella
• Taste environment
• Respond to food/poison
• chemotaxis

18

• Flagella
• embedded in cell membrane
• project as strand
• Flagellin (protein) subunits
• move cell by propeller like action

19
Axial filaments

• spirochetes
• similar function to flagella
• run lengthwise along cell
• snake-like movement

20
Making Wall-less Forms

• Result from action of
• enzymes lytic for cell wall
• antibiotics inhibiting peptidoglycan biosynthesis
• Usually non-viable
• Wall-less bacteria that dont replicate
• spheroplasts (with outer membrane)
• protoplasts (no outer membrane).
• Wall-less bacteria that replicate
• L forms

21
Naturally Wall-less Genus

• Mycoplasma

22
Pili (fimbriae)

• hair-like projections of the cell
• sexual conjugation
• adhesion to host epithelium

23
Capsules and slime layers

• outside cell envelope
• well defined capsule
• not defined slime layer or glycocalyx
• usually polysaccharide
• often lost during in vitro culture
• protective in vivo

24
Endospores (spores)

• Dormant cell
• Produced when starved
• Resistant to adverse conditions
• - high temperatures
• - organic solvents
• contain calcium dipicolinate
• Bacillus and Clostridium