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20 Cards in this Set
- Front
- Back
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Biogeochemical Cycling |
Metabolic degradation of biomass Elements cycle through the biosphere |
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Elemental composition |
Biogenic element proportions Similar in bacteria and humans Mostly Carbon |
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Elemental cycling changes |
Oxidation states Physical condition Metabolic activity |
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Carbon oxidation states -4 -2 0 2 4 |
methane
methanol/ hydrocarbons carbohydrates/ glucose formic acid carbon dioxide/bicarbonate ion |
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Carbon cycling |
Land: CO2 fixation into soil humus, slow Atmospheric: rapid Oceans: organic matter decomposition Sediments: large reservoir, long turnover |
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CO2 Fixation |
Usually via photosynthesis sometimes chemosyntheses |
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Oxygenic Photosynthesis |
higher plants, eukaryotic microalgae, cyanobacteria CO2 + H2O --> CH2O + O2 |
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Anoxygenic photosynthesis |
Purple sulfur, green sulfur CO2 + H2S --> CH2O + S |
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Respiration |
Occurs in dark and light CH2O + O2 -->CO2 + H2O |
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Decomposition of organic matter |
Catabolic energy yielding reactions, organotrophs photosynthetic fixed C is remineralized to CO2 and CH4 Net positive rate of photosynthesis over respiration --> net biomass production Oxidative/reductive balance important |
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know this |
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Methanotrophs |
Ch4 --> CO2 MMO- methane monooxygenase catalyses methanol step Microaerophilic gradient organisms |
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Anoxic Decomposition |
1. Hydrolysis of polymers 2. Primary fermentations - creates reactants for synotrophs 3. secondary fermentations (H2 producing fatty acid oxidizing synotrophs) 4. H2 consumption by methanogens and acetogens |
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Synotroph conditions |
H2 concentration must be low Methanogens help maintain this |
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Consortium |
Community members acting in cooperation to complete anoxic decomposition |
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Interspecies H2 Transfer |
Ethanol fermenting synotrophs create H2 that is used by H2 utilizing methanogens |
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Other Organic compounds --> methane |
1. Fermentation of glucose
2. Butyrate fermenting synotrophs that create H2 3. Acetotrophic methanogenisis 4. Acetogenisis from H2 |
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Rumen Fermentation |
glucose --> acetate, propionate, butyrate, CO2, CH4, H2O Do not possess cellulases. Methanogens process food to VFA VFA absorbed in blood and oxidized for energy |
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Vertebrate digestive systems |
Differ depending on diet Colonic, cecal, rumen fermenters |
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Ch4 vs CO2 |
CH4 is 30x ore potent, CO2 is more abundant |
