Chapter 27 - Prokaryotes

Decomposition life depends on recycling of chemical

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Unformatted text preview: Life depends on recycling of chemical elements between biological & physical components of the ecosystem life would stop without them Indispensable link in recycling - unlock organic molecules of corpses & waste products release back to biosphere Return non-living components of environment (air, soil, water) to pool of organic compounds Autotrophic prokaryotes make organic compounds from CO2 only organism other than plants Only organisms to metabolize non-organic molecules - iron, sulfur, nitrogen & hydrogen -metabolize just about anything Metabolic diversity of prokaryotes is the key Many prokaryotes are symbiotic often interact in groups symbiosis - living together provide nutrients to colon -over 500 different bacteria in our colon "close symbiotic relationships" Symbiosis = An ecological relationship between organisms of different species that are in direct contact. we help them and they help us Host-Symbiont Three types of symbiotic relationships: (1) Mutualism - both benefit (2) Commensalism - one receives benefits while neither harming nor helping the other very rare (3) Parasitism - one (parasite) benefits at death or significant survival issues expense of the host frequently Pathogenic Prokaryotes cause many human diseases cause 1/2 of all human disease some are opportunistic Streptococcus pneumonia - live in throats of healthy people - cause pneumonia when defenses down only when immune system is down does it multiply and cause infection First to connect disease to specific bacteria was Robert Koch - anthrax & tuberculosis Koch s Postulates (1) Find the same pathogen in each diseased indiv. (2) Isolate & grow in pure culture (3) Induce the disease in experimental animals by transferring the pathogen from culture mouse for example (4) Isolate the same pathogen from experimental animal after disease develops How do they cause disease? (1) Some invade tissue (directly) results in body's responseex: inflammation (2) Produce poisons exotoxins - proteins secreted by prokaryote botulism - 1 g - kill 1x106 endotoxins – lipopolysaccharide components of the outer membranes of certain gram-negative bacteria external membrane Are released when bacteria die. Salmonella typhi - typhoid fever Sanitation has significantly reduced disease & extended life expectancy. Antibiotics have saved lives Continuing threat Lyme disease - most widespread pest-carried disease in US - spirochete bacterium Evolution of antibiotic-resistant strains - serious health threat -tuberculosis exacerbated by imprudent antibiotic use and horizontal gene transfer take all antibiotics- natural selection; only killing off most susceptible to meds, not killing off most resistant Horizontal gene transfer can also spread genes associated with virulence – turn harmless prokaryotes into fatal pathogens. E. coli strain O157:H7 causes bloody diarrhea 1,387 out of 5,416 genes in O157:H7 have no counterpart in the harmless strain K-12 good bad Not true about peptidoglycan D. it is not found in cell walls of all prokaryotes Not promote horizontal gene transfer D. endospore formation lime disease tick Use of prokaryotes in research & technology (1) Used extensively in modern research (2) Bioremediation - use of organisms to remove pollutants from water, air & soil Treat sewage Used to decompose petroleum compounds pesticides, oil spills and radioactive wastes (3) Metabolic factories for commercial products Produce acetone, butanol, vitamins & antibiotics Convert milk to yogurt & cheese...
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