Lecture - Microbiology

Lecture - Microbiology - Prokaryotes, Viruses, and...

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Unformatted text preview: Prokaryotes, Viruses, and Protistans Microorganisms Single-celled organisms that are too small to be seen without a microscope Bacteria are the smallest living organisms Viruses are smaller but are not alive The Prokaryotes Only two groups Archaebacteria and Eubacteria Arose before the eukaryotes Prokaryotic Characteristics No membrane-bound nucleus Single chromosome Cell wall in most species Prokaryotic fission Metabolic diversity Prokaryotic Body Plan bacterial flagellum pilus capsule cell wall plasma membrane DNA ribosomes in cytoplasm Bacterial Shapes coccus bacillus spirillum Archaebacteria Methanogens Extreme halophiles Extreme thermophiles Archaebacteria Habitats Eubacteria Includes most familiar bacteria Have fatty acids in plasma membrane Most have cell wall; always includes peptidoglycan Classification based largely on metabolism Metabolic Diversity Photoautotrophs Chemoautotrophs Chemoheterotrophs Bacterial Genes Bacteria have a single chromosome Circular molecule of DNA Many bacteria also have plasmids Self-replicating circle of DNA that has a few genes Can be passed from one cell to another Prokaryotic Fission Video: E. coli Reproduction http://www.college.ucla.edu/webproject/micro7/l Conjugation nicked plasmid in donor cell conjugation tube to recipient cell The Normal Flora The normal flora of humans is exceedingly complex and consists of more than 200 species of bacteria. The mixture of organisms regularly found at any anatomical site is referred to as the normal flora . A Friendly Bacteria: E. coli Commonly inhabits the intestines of vertebrates E. coli does not normally infect us Many benefits: vitamin K and the B complex are produced by E. coli prevent colonization by pathogens stimulate the production of cross-reactive antibodies E. coli strain O157:H7. A Dangerous Form This mutant can be transmitted in food or water Think White Water and the Jack in the Box hamburger incidents Both made national news when many people became ill and some died. Sewage Pollution Indicator E. coli in streams, drinking water and surface waters of all kinds may indicate a problem with sewage and or farm runoff. Testing for unusual levels of these organisms is routinely done by public health officials Parks, swimming pools, restaurants etc may be closed if E. coli is detected E. coli Photos EM cells Culture plate Park settles last E. coli suit Patricia Guthrie - Staff Friday, December 15, 2000 The last of a dozen lawsuits, filed by families of children sickened in a 1998 E. coli outbreak tied to Cobb County's sickened in a 1998 E....
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Lecture - Microbiology - Prokaryotes, Viruses, and...

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