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73 Cards in this Set
- Front
- Back
What do the electron carries do in the ETS? |
They sequentially transfer electrons to the carrier of the nest higher reduction potential ( or the next stronger electron acceptor |
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Electron flow through the ETS begins with ________ and ultimately _________ |
an initial electron donor from outside the cell and ultimately transfers all electrons to terminal electron acceptor that leaves the cell |
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What is embedded in a membrane that separates two compartments? |
The ETS |
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What two compartments does the ETS separate and why? |
Two aqueous compartments and to maintain an ion gradient generated by the ETS |
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The ETS is composed of ? |
protein complexes and cofactors |
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Protein complexes called oxidoreductases include |
cytochromes and noncytochrome proteins |
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What are cytochromes? |
colored proteins whose absorbance spectrum shifts when there is a change in redox state |
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The ETS complexes generate |
a proton motive force |
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What does the proton motive force do? |
it is directed inward and drives protons into the cell |
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What does the proton potential drive? |
ATP synthesis, ion transport and flagellar rotation. |
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What do electron carriers contain for electron transfers? |
metal ions and or conjugated double bonded ring structures |
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Where does a substrate dehydrogenase receive a pair of electrons? |
from a particular reduced substrate like NADH, NADH dehydrogenase |
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How are protons pumped? |
By substrate dehydrogenase and terminal oxidase. |
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substrate dehydrogenases or |
oxidoreductases |
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How are protons consumed? |
by combining with the terminal electron acceptor like combining with oxygen to make water |
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What determines the number of protons pumped by a bacterial ETS? |
environmental conditions like the concentration of the substrate and terminal electron acceptor |
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The proton potential drives ATP synthesis through |
membrane bound ATP synthase |
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How many protons drive each cycle of ATP synthesis and what is synthesized |
three protons needed to make one molecule of ATP |
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Anaerobic terminal electron acceptors |
accept electrons from a specific reductase complex of ATP |
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What are some anaerobic terminal electron acceptors? |
Nitrogen and sulfur oxyanions, oxidized metal cations, and oxidized organic substrates |
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How is nitrate reduced by bacteria? |
Nitrate, nitrite, nitric oxide, nitrous oxide and ultimately nitrogen gas. |
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Nitrate and nitrite could be reduced to |
ammonium ion- a product that alkalinizes the environment |
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Sulfate is successivley reduced by bacteria to |
sulfite, thioslfate, elemental sulfur, and hydrogen sulfide. |
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Where are sulfate reducers especially prevalent |
seawater |
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Dissimilatory metal reduction |
a form of anaerobic respiration where oxidized metal ions are reduced by bacteria in soil and aquatic habitats |
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Name some oxidized metal ions |
Fe 3+ and Mn 4+ |
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The geochemistry of natural environments is largely shaped by |
anaerobic bacteria and archaea |
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The acquisition of energy by oxidation of inorganic electron donors |
Lithotrophy or chemolithotrophy |
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6 things included in lithotrophy |
sulfur oxidation iron oxidation nitrogen oxidation hydrogenotrophy methanogenesis methane oxidizers |
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sulfuric acid production leads to |
extreme acidification, damaging stone structures and poisoning mine drainage |
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sulfur oxidation includes |
oxidation of H2S to sulfur or to sulfuric acid by sulfur-oxidizing bacteria. |
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What usually accompanies sulfur oxidation and in what form |
Iron oxidation ( rust) |
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Nitrogen oxidation includes |
successive oxidation of ammonia to hydroxlamine, nitrous acid and nitric acid. |
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What uses hydrogen gas as an electron donor |
Hydrogenotrophy |
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Hydrogen has sufficient |
reducing potential to donate electrons to nearly all biological electron acceptors including chlorinated organic molecules (through dehalorespiration) |
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occurs by oxidation of H2 by carbon dioxide to form methane |
Methanogenesis
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Methanogenesis is performed only by |
the methanogen groups of archaea |
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Methane oxidizers use O2, nitratem or sulfate to |
oxidize the methane produced by methanotrophs |
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The metabolic ability to absorb and covert solar energy into chemical energy for biosynthesis |
Photosynthesis |
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5 things of photosynthesis |
Bacteriorhodopsin The antenna complex Thylakoids The oxygenic Z pathway in cyanobacteria and chloroplast oxygenic photosynthesis generates 3 atp and 2 nadph |
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a light-driven proton pump that supplements hetertrophy in haloarchaea |
bacteriorhodopsin |
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What is found in marine proteobacteria |
proteorhodopsin |
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What captures light for transfer to the reaction center in cholorphyll-based photosynethsis |
The antenna complex of chlorophylls and other photopigments |
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folded membranes within phototrophic bacteria or chloroplasts |
Thylakoids |
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Thylakoid membranes extend |
area for chlorophyll light absorption and they separate two compartments to form a proton gradient |
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This includes homologs of photosystems I and II. |
The oxygenic Z pathway in cyanobacteria and chloroplasts |
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What happens in the Oxygenic Z pathway in cyanobacteria and chloroplast |
Eight photons are absorbed and two electron pairs are removed from 2 H2O ultimately producing O2 |
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Oxygenic photosynthesis generates |
3 atp and 2 nadph per 2 H2O photolyzed and O2 produced |
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What is used to fix carbon dioxide into biomass |
ATP and NADPH |
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Electrochemical potential or voltage across a membrane may be used to |
power ATP synthesis, nutrient uptake, or motility |
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ETS redox reactions |
the transfer of electrons from a reduced electron donor to an oxidized electron acceptor Energy is converted to an ion or voltage potential across the memebrane |
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Where does ETS occur in prokaryotes |
at the cytoplasmic membrane |
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Where does ETS occur in eukaryotes |
the inner mitochondrial membrane |
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ETS ultimately pumps |
protons out of the cell generating the proton motive force
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Respiratory ETS and ATP synthesis |
An ETS much be able to harvest energy in small steps such as pmping protons across the membrane |
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Anaerobic respiration |
makes it so that bacteria and archaea can exist in a place where there isn't oxygen |
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anaerobic respiration terminal electron acceptors |
nitrogen and sulfate |
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What plays a role in recycling the elements in the biosphere |
Chemolithotrophy |
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Chemolithotrophy is a form of |
energy yielding metabolism whereby reduced minerals can serve as electron donors for ETS |
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The Anaerobic oxidation of ammonium to nitrogen gas |
does yield energy for growth and plays an important role in cycling nitrogen back into the atmosphere |
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a form of hydrogenotrophy in which chlorine is removed from a compound and replaced by a hydrogen |
Dehalorespiration |
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What is commonly used to supplement traditional commercial mining endeavors |
microbial leeching by oxidixing minerals and dissolving the metals from rocks. |
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Where does methanogenesis is commonly found? |
landfills and the digestive systems of cows and humans |
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Lithotrophy corresponds to energy derived from |
compounds not containing any carbon |
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ogranotrophy derives energy from |
breakdown of compounds with at least one carbon-carbon bond |
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ancient form of phototrophy |
bacteriorhodopsin |
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Three things of bacteriorhodopsin |
relies on a single-protein light driven proton pump commonly found in haloarchaea absorbs light in the green range and reflects it in the red and blue ranges appearing purple. |
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Two forms of phototrophy |
bacteriorhodopsin and proteorhodopsin |
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a bacterial membrane protein that contains retinal and acts as a light-driven proton pump |
proteorhodopsin |
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light-absorbing pigments which have a light-absorbing electron carrier referred to as a chromophore. |
Chlorophylls |
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Where are chlorophylls found? |
Bacteria and plants |
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Chlorophylls of anaerobic phototrophs absorb |
in the infrared range and appear a deep purple or brown |
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An organism that uses all the metabolic options- heterotrophy, lithotrophy and photosynthesis is referred to as |
asfacultative phototrophy |