Handouts Unit 2

Handouts Unit 2 - MBI111 Handout 3 Microorganisms as...

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MBI111 Handout 3 08/10/2007 19:23:00 Microorganisms as Parasitic Agents Description of Microorganisms * General characteristics o eukaryotes vs. prokaryotes vs. viruses + prokaryotes - small, "simple" cells that typically have a cell walland cytoplasmic membrane surrounding their cytoplasm, which contains ribosomesand a single chromosome (contains genes made up of DNA), but have nomembranes surrounding their nucleus or organelles + eukaryotes - large, complex cells with a nucleus that containsmultiple chromosomes (contains genes of DNA) surrounded by a membrane and cytoplasm containing ribosomes and membrane-bound organelles, such as mitochondria, vacuoles, chloroplasts (plants only), golgi bodies, etc. + viruses - non-cellular, non-living entities, made up of genetic information (DNA or RNA) enclosed in a protein coat (some also have a membranecalled an envelope), which can reproduce themselves only by infecting cells and utilizing cellular materials and processes o growth - process of cell enlargement and proliferation (increase in number) + nutritional requirements - water; essential elements(C, H, O, N, P, S); trace elements (Ca, Mg, Fe, Na, K, Zn, Co, Mn, etc.); organic growth factors - vitamins, essential nutrients, etc.;energy + physical requirements # temperature - cells may grow best below 20°C (psychrophilic), or from 20 to 40°C (mesophilic), or above 40°C (thermophilic) # oxygen - aerobes, facultative aerobes, microaerophiles, anaerobes # pH - most cells "prefer" neutral conditions (pH between 6 and 8), but many can thrive in acid (pH down to 3) or alkali (pH up to 10) # salts - regulate enzyme activity, osmotic pressure * Bacteria o morphology - these prokaryotes are typically ~0.2-2 x 1-5 um + cytoplasmic membrane - this lipid/protein outer boundary of the cytoplasm regulates what goes in and out of the cell (permeability) + ribosomes - small RNA/protein particles required for protein synthesis + chromosome - large single strand of DNA that contains the "blueprint" for all cell structure and activity in regions called genes
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+ plasmids - DNA that contains only a few genes and is exchanged between bacteria (codes for antibiotic resistance or virulence factors) + granules - storage bodies (may contain phosphates, iron, lipids,etc.) + cell wall - rigid structure (peptidoglycan +/- lipopolysaccharide) that protects against osmotic pressure damage and provides cell shape - cylindrical (bacillus); spherical (coccus); helical (spirillum) + capsule - polysaccharide "coatings" secreted by cells (adhesins) + flagella - long, thin protein (flagellin) polymers that provide motility + pili - long, thin protein (pilin) polymers that act as adhesins + endospore - thick-walled protective structures; highly resistant to adverse environmental conditions (high temperature, drying, O2, etc.) o physiology + nutrition for bacteria in general may be (pathogens are heterotrophic):
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This note was uploaded on 04/07/2008 for the course MBI 111 taught by Professor Clark during the Spring '07 term at Miami University.

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Handouts Unit 2 - MBI111 Handout 3 Microorganisms as...

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