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Dr. Alvin Fox.

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Presentation on theme: "Dr. Alvin Fox."— Presentation transcript:

1 Dr. Alvin Fox

2 Key Words Prokaryotic Outer membrane Eubacteria (Bacteria)
Periplasmic space Archaebacteria (Archaea) 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


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 + Gram - (e.g. animal) Flagellum
Nucleoid Rough endoplasmic reticulum Cell membrane Cell wall Nucleus Gram - Cell (inner) membrane Outer membrane Ribosomes Granule Cell wall Capsule Pili Cytoplasm Mitochondria

10 Plasmids Bacteria 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). Cell Wall Cytoplasm Cell membrane The cell wall is outside of cell membrane rigid, protecting cell from osmotic lysis.

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

Outer Membrane (Major permeability barrier) Lipopolysaccharide Porin Braun lipoprotein Periplasmic space Degradative enzyme Periplasmic binding protein Permease Inner (cytoplasmic) membrane Cytoplasm

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 don’t replicate: spheroplasts (with outer membrane) protoplasts (no outer membrane). Wall-less bacteria that replicate L forms

21 Naturally Wall-less Genus

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

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