Term
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Definition
| the chain of electron carriers into which electrons enter to begin oxidative phosphorylation |
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Term
| What type of proteins contain a very tightly, sometimes covalently, bound flavin nucleotide (either FMN or FAD)? |
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Definition
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Term
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Definition
| a single electron equivalent transferred in an oxidation-reduction reaction |
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Term
| ubiquinone (coenzyme Q) (Q) |
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Definition
| a lipid-soluble benzoquinone with a long isoprenoid side chain |
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Term
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Definition
| proteins with characteristic strong absorption of visible light due to their iron-containing heme prosthetic groups |
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Term
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Definition
| proteins in which the iron is present not in heme but in association with inorganic sulfur atoms or with the sulfur atoms of Cys residues in the protein or both |
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Term
| Rieske iron-sulfur proteins |
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Definition
| a variation of iron-sulfur proteins in which one Fe atom is coordinated to two His residues rather than two Cys residues |
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Term
| complex I (NADH:ubiquinone oxidoreductase) (NADH dehydrogenase) |
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Definition
| a large enzyme composed of 42 different polypeptide chains including an FMN-containing flavoprotein & at least six iron-sulfur centers |
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Term
| 2 processes catalyzed by complex I |
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Definition
1. the exergonic transfer to ubiquinone of a hydride ion from NADH & a proton from the matrix
2. the endergonic transfer of four protons from the matrix to the intermembrane space |
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Term
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Definition
| ex) how complex I acts as a proton pump driven by the energy of electron transfer to catalyze a reaction; a reaction that moves protons in a specific direction from one location to another |
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Term
| What is the only membrane-bound enzyme in the citric acid cycle? |
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Definition
| complex II (succinate dehydrogenase) |
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Term
| 3 electron transfers catalyzes by the flavo-protein acyl-CoA dehydrogenase for the first step in the beta oxidation of fatty acyl-CoA |
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Definition
1. from the substrate to the FAD of the dehydrogenase
2. to electron-transferring flavoprotein
3. to ETF:ubiquinone oxidoreductase |
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Term
| complex III (cytochrome bc1 complex) (ubiquinone:cytochrome c oxidoreductase) |
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Definition
| the respiratory complex that couples the transfer of electrons from ubiquinol to cytochrome c with the vectorial transport of protons from the matrix to the intermembrane space |
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Term
| What is the Q cycle a model for? |
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Definition
| based on the structure of complex III & detailed biochemical studies of redox reactions, it models the passage of electrons & protons through the complex |
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Term
| complex IV (cytochrome oxidase) |
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Definition
| in the final step of the respiratory chain, it carries electrons from cytochrome c to molecular oxygen, reducing it to H2O |
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Term
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Definition
| formed when the respiratory complexes in the intact mitochondrian tightly associate with each other in the inner membrane; functional combinations of two or more different electron-transfer complexes |
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Term
| 2 components to the proton-motive force |
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Definition
1. the chemical potential energy due to the difference in concentration of a chemical species in the two regions separated by a membrane
2. the electrical potential energy that results from the separation of charge when a proton moves across the membrane without a counterion |
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Term
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Definition
| renders generated hydrogen peroxide harmless |
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Term
| What does the chemiosmotic model represent? |
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Definition
| the electrochemical energy inherent in the difference in proton concentration & the separation of charge across the inner mitochondrial membrane (the proton-motive force) drives the synthesis of ATP as protons flow passively back into the matrix through a proton pore in ATP synthase |
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Term
| Why was F1 originally called "F1 ATPase"? |
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Definition
| isolated F1 catalyzes ATP hydrolysis |
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Term
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Definition
| a mechanism in which three active sites of F1 take turns catalyzing ATP synthesis |
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Term
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Definition
| the gamma subunit should rotate in one direction when F0F1 is synthesizing ATP & in the opposite direction when the enzyme is hydrolyzing ATP |
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Term
| adenine nucleotide translocase |
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Definition
| a molecule integral to the inner membrane which binds ADP3- in the intermembrane space & transports it into the matrix in exchange for an ATP4- molecule simultaneously transported outward |
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Term
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Definition
| a membrane transport system essential to oxidative phosphorylation; promotes symport of one H2PO4- & one H+ into the matrix |
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Term
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Definition
| a complex of the ATP synthase & both translocases; can be isolated from the mitochondria by gentle dissection with detergents, suggesting that the functions of these three proteins are very tightly integrated |
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Term
| What is the most active NADH shuttle (functions in the liver, kidney, & heart mitochondria)? |
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Definition
| the malate-aspartate shuttle |
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Term
| What NADH shuttle is used by skeletal muscle & brain? |
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Definition
| glycerol 3-phosphate shuttle |
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Term
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Definition
| dependence of the rate of O2 consumption on the availability of the Pi acceptor (ADP) for respiration |
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Term
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Definition
| the ratio of the maximal rate of ADP-induced O2 consumption to the basal rate in the absence of ADP |
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Term
| 2 processes encompassed by photosynthesis in plants |
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Definition
1. the light-dependent reactions (light reactions; occur only when plants are illuminated)
2. carbon-assimilation reactions (carbon-fixation reactions; misleadingly called "dark reactions"; driven by products of the light reactions) |
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Term
| How are the flattened, membrane-surrounded vesicles (sacs) called "thylakoids" arranged? |
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Definition
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Term
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Definition
| the thylakoid membranes which contain the photosynthetic pigments & the enzyme complexes that carry out the light reactions & ATP synthesis |
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Term
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Definition
| contains most of the enzymes required for the carbon-assimilation reactions |
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Term
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Definition
| when leaf extracts containing chloroplasts are illuminated, they evolve O2 & reduce a nonbiological (artificial) electron acceptor added to the medium (the Hill reagent) |
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Term
| How does the energy of a single photon change across the color spectrum? |
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Definition
| the energy of a single photon is greater at the violet end of the spectrum than at the red end; shorter wavelength corresponds to higher energy |
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Term
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Definition
| a quantity of energy that a photon must contain to be absorbed; the quantum exactly matches the energy of the electronic transition |
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Term
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Definition
| a molecule that has absorbed a photon; generally unstable |
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Term
| How does a molecule return to the ground state? |
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Definition
| an electron lifted into a higher-energy orbital usually returns rapidly to its lower-energy orbital, thus decaying the excited molecule to the stable ground state; a molecule gives up the absorbed quantum as light or heat using it to do chemical work |
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Term
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Definition
| light emission accompanying decay of excited molecules; always at a longer wavelength than that of the absorbed light |
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Term
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Definition
| think: just like the photon is a quantum of light energy; a quantum of energy passed from an excited molecule to another molecule in a process called "exciton transfer" |
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Term
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Definition
| the most important light-absorbing pigments in the thylakoid membranes; green pigments with polycyclic, planar structures resembling the protoporphyrin of hemoglobin except that Mg2+ (not Fe2+) occupies the central position |
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Term
| 2 structural components of all chlorophylls |
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Definition
1. a long phytol side chain, esterified to a carboxyl-group substituent in ring IV
2. a fifth five-membered ring not present in heme |
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Term
| light-harvesting complexes (LHCs) |
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Definition
| formed because chlorophyll is always associated with specific binding proteins; chlorophyll molecules are fixed in relation to each other, to other protein complexes, & to the membrane |
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Term
| What do cyanobacteria & red algae employ as their light-harvesting pigments? |
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Definition
| phycobilins (such as phycoerythrobilin & phycocyanobilin) |
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Term
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Definition
| when phycobilins are covalently linked to specific binding proteins; they associate in highly ordered complexes called "phycobilisomes" that constitute the primary light-harvesting structures in some microorganisms |
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Term
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Definition
| secondary light-absorbing pigments found in the thylakoid membranes in addition to chlorophylls; called "carotenoids" |
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Term
| 3 colors that carotenoids can be |
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Definition
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Term
| 2 most important carotenoids |
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Definition
1. beta-carotene (a red-orange isoprenoid)
2. lutein (the yellow carotenoid) |
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Term
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Definition
| functional arrays into which the light-absorbing pigments of thylakoid or bacterial membranes are arranged |
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Term
| Even though all the pigment molecules in a photosystem can absorb photons, which are the only ones that are specialized to transduce light into chemical energy? |
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Definition
| a few chlorophyll molecules associated with the photo-chemical reaction center |
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Term
| light-harvesting (antenna) molecules |
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Definition
| the pigment molecules in a photosystem which are not associated with the photo-chemical reaction center |
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Term
| To what is photosystem I (PSI) structurally & functionally related to? |
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Definition
| the type I reaction center of green sulfur bacteria |
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Term
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Definition
| the soluble protein that carries electrons between the two photosystems; a one-electron carrier functionally similar to cytochrome c of mitochondria |
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Term
| What does a Z scheme outline? |
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Definition
| the pathway of electron flow between the two photosystems & the energy relationships in the light reactions |
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Term
| To what structure does protein-bound plastoquinone PQA pass its electrons? |
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Definition
| a more loosely bound plastoquinone (PQB) |
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Term
| To what does phylloquinone pass an electron that it receives? |
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Definition
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Term
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Definition
| an iron-sulfur protein loosely associated with the thylakoid membrane |
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Term
| ferredoxin:NADP+ oxidoreductase |
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Definition
| the flavoprotein that serves as an electron carrier to transfer electrons from reduced ferredoxin to NADP+ |
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Term
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Definition
| electron flow from PSII through the cytochrome b6f complex, then through PSI to NADP+ |
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Term
| cyclic photophosphorylation |
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Definition
| proton pumping by the cytochrome b6f complex & phosphorylation of ADP to ATP |
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Term
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Definition
| when the association of LHCII with PSI & PSII changes in the short term (due to the dependency on light intensity & wavelength) in the chloroplast |
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Term
| oxygen-evolving complex (water-splitting complex) |
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Definition
| a molecular device which passes four electrons one at a time to P680+ |
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Term
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Definition
| pigment-containing membranous structures in which light-dependent ATP production takes place |
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