HIV AND INFULENZA VIRUS PPT HIV PPT INFULENZA VIRUS PPT
Bacteria &; prokaryotes
1. Bacteria 1
Bacteria
Chapter 5
Classification of bacteria is
‘murky’
A “Muddle in the Middle”
Few distinctive characteristics
Genetically promiscuous
Traditional classification:
anatomical features
staining characteristics
metabolic properties
Newer approach
Genetic analysis
Bergey’s manual is the ‘Bible’
3. Bacteria 3
Classification based upon
anatomical features
Other unusual bacteria
Spirochetes
Cell wall-less
Stalked
Filamentous
Myxobacteria fruiting bodiesStreptomyces
4. 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
5. Bacteria 5
Classification based upon
metabolism
-- will explore further later
Heterotrophic
Autotrophic
Photosynthetic 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
6. Bacteria 6
Why are bacteria so small?
Size affects ‘surface to volume’ ratio
Advantages of large S/V:
diffusion rates
metabolic rates
reproductive rates
Limits to size reduction?
‘defective’ bacteria
Really big bacteria?
-- Epulopiscium fishelsoni
Epulopiscium web site
http://www.micro.cornell.edu/cals/micro/research/labs/
angert-lab/epulopiscium.cfm
7. Bacteria 7
Why study Bacterial Cell Structure?
Mechanisms of virulence
Drug development
Identification
Some cell exterior structures
cell membrane (lipid bilayer)
cell wall (Gram-pos vs Gram-neg)
glycocalyx (capsule vs slime layer)
flagellum (prokaryotic vs eukaryotic)
pilus (adhesion vs sex)