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44 Cards in this Set
- Front
- Back
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Why will respiratory paths almost always choose oxygen as their electron acceptor? |
- Oxygen gives a large free energy difference yielding more energy |
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Fermentation |
- The terminal electron acceptor is generally an intermediate of the catabolic pathway - Most ATP is synthesize by substrate-level phosphorylation, whereby ADP is phosphorylated to ATP |
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Why does fermentation produce less ATP than respiration? |
Immediate don't utilize as much energy |
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Substrate-level Phosphorylation |
- Harvest energy to pump protons across a membrane |
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Lithotroph |
Depends on inorganic compounds as electron donors |
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Chemotroph |
Obtain energy by oxidizing inorganic or organic materials |
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Organotroph |
Obtains energy from organic compounds |
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Heterotroph |
Cannot generate its own food and instead take in organic matter from outside sources |
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Autotroph |
Utilize light or inorganic chemical reactions to produce complex organic compounds |
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Phototroph |
An organism that uses light as its principle source of energy |
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Biogeochemical Cycling |
- "The sum of the microbial and chemical processes that dire the flow of elements between sediments, water, and the atmosphere" - Habitats with high redox potential are more likely to accept electrons - Habitats with low redox potential are more likely to donate electrons |
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Methane Hydrates |
Deposits of methane that are locked within the earth |
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Mineralization |
- Where an organic compound becomes an inorganic carbon - (e.g., the formation of shells and bones) |
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Methanogenesis |
- Reduction of carbon to methane - Carried out by Archaea |
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Anoxygenic Photosynthesis |
- Where water is utilized as an electron onto to make oxygen - (e.g., diatoms, cyanobacteria) |
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Chemolithotroph |
Where electrons com from inorganic sources |
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What carries out nitrogen fixation |
Bacteria and Archaea - e.g., rhizobium |
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Assimilatory Nitrate Reduction |
Taken up in an organic compound |
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Dissimilatory Nitrate Reduction |
The direct reduction of nitrate to ammonium |
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Ammonification |
Removed from protein and return back to ammonia |
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NO3- |
Nitrate - Fully-oxidized form |
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NH3 |
Ammonia |
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NH4+ |
NH4+ |
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NO2- |
Nitrogen dioxide |
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N2O |
Nitrous oxide |
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N2 |
Nitrogen gas |
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Denitrification |
A series of steps to return the nitrogen to the ammonia form |
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Nitrogen Fixation |
Process by which atmospheric nitrogen is converted to ammonia |
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Complete Nitrification |
- From ammonium to nitrate - Possible via nitrospira |
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Which organisms are capable of fixing nitrogen? |
- Azatobacter - Cyanobacteria - Rhizobium - Clostridium |
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Which organisms are capable of carrying out nitrification? |
- Nitrosomonas - Nitrobacter - Nitrospera |
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What is the fully oxidized form of sulphur? |
Sulphate |
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Sulphur Cycle |
- Sulphate is reduced by microbes and plants for use in amino acids - During anaerobic respiration, sulphate may serves as the terminal electron acceptor - Chemolithotrophs may use sulphur compounds as electron donors - DMS and DMSO are important compounds in marine environments. DMS is broken down by compatible solutes of aquatic organisms |
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Assimilatory Sulphate Reduction |
Sulphate is reduced by microbes and plants for use in amino acids |
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Sulpha Disproportionation |
A process in which the reactant is both oxidized and reduced |
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Compatible Solutes |
Prevent the exiting of water from the cell |
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Desulfurylation |
The reverse process of assimilation |
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Which organisms are important in sulfide/sulfur oxidation? |
Green and purple phototrophic bacteria |
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The Iron Cycle |
- Primarily the interchange of ferrous iron (Fe2+) to ferric iron (Fe3+) - An essential element - At neutral pH, iron is insoluble |
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What happens when there are high levels of nitrate or ammonium in the cell? |
The rate of organic carbon fixation is increased |
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What happens when levels of ammonium are low in the cell? |
The rate of photosynthesis is slowed |
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What are the greenhouse gases? |
- CO2 - CH4 - Nitrogen oxides (NO, N2O) - They trap heat on the earth's surface |
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Haber and Bosch |
- Invented the process of chemical fixation of nitrogen to ammonium - Useful in fertilizers - Though fertilizers have allowed for more extensive farming, extra NH4+ in the soil has perturbed the nitrogen cycle |
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Eutrophication |
The leeching of nitrogen-containing fertilizers that can cause algal blooms in bodies of water and death of certain organisms |
