Bacteria1 Chapter 5 Classification of bacteria is ‘murky’ A “Muddle in the Middle” Few...
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Transcript of Bacteria1 Chapter 5 Classification of bacteria is ‘murky’ A “Muddle in the Middle” Few...
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Bacteria 1
Bacteria Chapter 5
Classification of bacteria is ‘murky’
A “Muddle in the Middle”Few distinctive characteristicsGenetically promiscuous
Traditional classification:anatomical featuresstaining characteristicsmetabolic properties
Newer approach
Genetic analysis
Bergey’s manual is the ‘Bible’
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Bacteria 2
Classification based upon anatomical features
3 common shapes
Some unusual shapes also:
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Bacteria 3
Classification based upon anatomical features
Other unusual bacteria
Spirochetes
Cell wall-less
Stalked
Filamentous
Myxobacteria fruiting bodies Streptomyces
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Bacteria 4
Classification based upon staining
Gram Positive vs Gram Negative
Hans Christian Gram -- 1884-- Crystal violet
Gram positive structure-- thick layer of peptidoglycan
Gram negative structure-- inner vs outer membranes-- lipopolysaccharides and endotoxins
Acid fast staining-- Mycobacterium
Penicillin action
Effect of penicillin
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Bacteria 5
Classification based upon metabolism -- will explore further later
Heterotrophic
AutotrophicPhotosynthetic bacteria
-- cyanobacteria -- purple sulfur bacteria
Chemoautotrophic
‘Metabolically defective’
Rickettsia
Chlamydia
Rocky Mountain Rocky Mountain Spotted fever wood tick R. rickettsii
Image from (and good source for more about Chlamydia)http://www.chlamydiae.com/docs/biology/biol_devcycle.asp
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Bacteria 6
Why are bacteria so small?Size affects ‘surface to volume’ ratio
Advantages of large S/V:diffusion ratesmetabolic ratesreproductive rates
Limits to size reduction?‘defective’ bacteria
Really big bacteria?-- Epulopiscium fishelsoni
Epulopiscium web sitehttp://www.micro.cornell.edu/cals/micro/research/labs/angert-lab/epulopiscium.cfm
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Bacteria 7
Why study Bacterial Cell Structure?Mechanisms of virulence
Drug development
Identification
Some cell exterior structurescell membrane (lipid bilayer)
cell wall (Gram-pos vs Gram-neg)
glycocalyx (capsule vs slime layer)
flagellum (prokaryotic vs eukaryotic)
pilus (adhesion vs sex)
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Bacteria 8
Cell Membrane Structure
Phospholipid bilayers
Membrane proteins
Membrane fluidity
Membranes ofthermophilic archaebacteria
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Bacteria 9
Bacterial Flagella
Prokaryotic vs eukaryotic
Arrangementsmonotrichous
lopho-
amphi-
peri-
How do we know movementis rotational?
Bacterial Flagella
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Bacteria 10
How do flagellatedbacteria move?
‘Run and Tumble’ patternChromatium motility
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Bacteria 11
Spirochetes -- very strange structure-- e.g., Borrelia, Treponema
Axial filaments
Outer sheath
Motility
Borrelia Movement
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Bacteria 12
Fimbriae and Pili
Fimbriae adhesion to surfaces
Pili (pilus)genetic recombination
other functions?
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Bacteria 13
The glycocalyx
Functionsadherencevirulenceprevent desiccation
Composition
Capsule layersvs
Slime layers“xantham gum”(Xanthomonas)
Strep Pneumo
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Bacteria 14
Endospores
Formation and regrowth
Special properties?-- desiccated-- DNA binding proteins-- Ca-dipicolinic acid
Magnetotactic bacteria-- possess magnetosomes
Endospore formation
Magnetotactic Bacteria