Microbiology for Environmental Health Officers. EHL0033 Prokaryotes 3

Transcription

1 Microbiology for Environmental Health Officers EHL0033 Prokaryotes 3

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3 Mutualism: bacterial headlights. The glowing oval below the eye of the flashlight fish (Photoblepharon palpebratus) is an organ harboring bioluminescent bacteria. The fish uses the light to attract prey and to signal potential mates. The bacteria receive nutrients from the fish.

4 Prokaryotes impacts on humans Harmful Illness Beneficial Essential tools in agriculture and industry

5 Pathogenic Prokaryotes

6 Exo and Endotoxins Poisons Exotoxins are proteins secreted by prokaryotes Endotoxins are lipopolysaccharide components of the outer membrane of gram negative bacteria

7 Bioremediation

8 a tentative phylogeny of some of the major taxa of prokaryotes based on molecular systematics

9 Structure of the Bacterial Cell

10 EUKARYOTES PROKARYOTES BACTERIA ARCHAEA

11 Prokaryotes (Bacteria) Eubacter "True" bacteria human pathogens clinical or environmental one kingdom Archaea Environmental organisms second kingdom

12 Eukaryotes Other cell-based life e.g. plants animals fungi

13 Prokaryotic Cell (versus Eukaryotic Cell) Not compartmentalized Cell membranes lack sterols (e.g. cholesterol) Single circular chromosome Ribosomal are 70S - subunits 30S 50S

14 A prokaryotic chromosome. The thin, tangled loops surrounding this ruptured E. coli cell are parts of a single ring of DNA (colorized TEM).

15 Bacteria versus Archaebacteria Eubacteria peptidoglycan (murein) muramic acid Archaebacteria pseudomurein no muramic acid

16 Shape

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19 Basic components of a bacterial cell

20 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

21 Flagella Arrangement Figure 4.7

22 Fimbriae/pili Shorter and less complex than flagella Helps adhere to surfaces Used for sex and communication

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24 Gram Positives have large cell wall and Teichoic acids

25 Gram negative cells have lipopolysaccharide

26 Typical Prokaryotic cell types Cell membrane Nucleoid Flagellum Cell wall Gram +ve cell Gram ve cell Pili Capsule Granule Cell (inner) membrane Outer membrane Ribosomes Cell wall

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

28 Gram-Negative Outer Membrane Figure 4.13c

29 How the gram stain works to differentiate between G+ and G-

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31 Plasma Membrane Phospholipid bilayer Peripheral proteins Integral proteins Transmembrane proteins Figure 4.14b

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33 Membrane is as viscous as olive oil. Proteins move to function Fluid Mosaic Model Phospholipids rotate and move laterally Figure 4.14b

34 Ribosomes Figure 4.6a

35 Ribosomes Figure 4.19

36 Endospores Resting and waiting stage Resistant to drying and other harsh conditions

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38 The Cell Envelope Gram Positive Gram Negative

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40 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.

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

42 GRAM POSITIVE CELL Degradative enzyme ENVELOPE Lipoteichoic acid Peptidoglycan-teichoic acid Cytoplasmic membrane Cytoplasm

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

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48 Axial filaments similar function to flagella run lengthwise along cell snake-like movement

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