Term
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Definition
| the conversion of CO2 to simple organic compounds which is catalyzed by enzymatic machinery found in the chloroplasts of green plants |
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Term
| CO2 fixation (carbon fixation) |
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Definition
| the specific reaction in which CO2 is incorporated into a three-carbon organic compound (the triose phosphate 3-phosphoglycerate) |
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Term
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Definition
| where most of the biosynthetic activities in plants occur; a family of self-reproducing organelles bounded by a double membrane & containing a small genome that encodes some of their proteins |
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Term
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Definition
| the sites of CO2 assimilation |
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Term
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Definition
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Term
| How can chloroplasts by converted to proplastids? |
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Definition
| by the loss of their internal membranes & chlorophyll; proplastids are interconvertible with amyloplasts |
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Term
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Definition
| the first stage in the assimilation of CO2 into biomolecules; condensation of CO2 with a five-carbon acceptor (ribulose 1,5-biphosphate) to form two molecules of 3-phospho-glycerate |
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Term
| 3 stages of carbon dioxide assimilation |
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Definition
1. fixation of CO2 into 3-phosphoglycerate
2. conversion of 3-phosphoglycerate to glyceraldehyde 3-phosphate
3. regeneration of ribulose 1,5-biphosphate from triose phosphates |
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Term
| Where is the 14C predominantly located in 3-phosphoglycerate? |
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Definition
| in the carboxyl carbon atom |
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Term
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Definition
| plants in which 3-phosphoglycerate is the first intermediate in carbon dioxide assimilation |
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Term
| ribulose 1,5-biphosphate carboxylase/oxygenase (rubisco) |
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Definition
| the enzyme that catalyzes incorporation of CO2 into an organic form |
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Term
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Definition
| overcomes inhibition by promoting ATP-dependent release of the ribulose 1,5-biphosphate, exposing the Lys amino group to nonenzymatic carbamoylation by CO2; followed by Mg2+ binding, this activates rubisco |
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Term
| 3-phospho-glycerate kinase |
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Definition
| a stromal molecule which catalyzes the transfer of a phosphoryl group from ATP to 3-phosphoglycerate to yield 1,3-biphosphoglycerate |
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Term
| glyceraldehyde 3-phosphate dehydrogenase |
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Definition
| the chloroplast-specific isozyme that catalyzes NADPH donating electrons in a reduction to produce glyceraldehyde 3-phosphate & Pi |
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Term
| What is the prosthetic group of transketolase & what does it require? |
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Definition
prosthetic group = thiamine pyrophosphate
requires = Mg2+ |
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Term
| sedoheptulose 1,7-biphosphate |
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Definition
| a seven-carbon molecule formed by aldolase combining erythrose 4-phosphate with dihydroxyacetone phosphate |
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Term
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Definition
| what the pentose phosphates formed in the transketolase reactions (ribose 5-phosphate & xylulose 5-phosphate) are converted to; it is phosphorylated to ribulose 1,5-biphosphate by ribulose 5-phosphate kinase |
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Term
| ferredoxin-thioredoxin reductase |
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Definition
| catalyzes the reaction in which electrons (with illumination) flow from photosystem I to ferredoxin which passes electrons to a small, soluble, disulfide-containing protein called "thioredoxin" |
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Term
| mitochondrial respiration |
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Definition
| carried out by plants in the dark; the oxidation of substrates to CO2 & the conversion of O2 to H2O |
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Term
| What causes photorespiration to occur? |
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Definition
| the lack of specificity of the enzyme rubisco |
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Term
| What causes the creation of metabolically useless 2-phosphoglycolate? |
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Definition
| molecular oxygen competes with CO2 at the active site & about once in every three or four turnovers, rubisco catalyzes the condensation of O2 with ribulose 1,5-biphosphate to form 3-phosphoglycerate & 2-phosphoglycolate |
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Term
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Definition
| converts 2 molecules of 2-phosphoglycolate to a molecule of serine & a molecule of CO2 |
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Term
| glycine decarboxylase complex |
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Definition
| oxidizes glycine to CO2 & NH3 with the concomitant reduction of NAD+ to NADH & transfer of the remaining carbon from glycine to the cofactor tetrahydrofolate |
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Term
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Definition
| the combined activity of the rubisco oxygenase & the glycolate salvage pathway to consume O2 & produce CO2 |
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Term
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Definition
| plants which use the carbon-assimilation method in which the first step is a reaction of CO2 with ribulose 1,5-biphsophate to form 3-phosphoglycerate |
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Term
| Where does the reaction catalyzed by phosphoenolpyruvate carboxylase which uses HCO3- as the substrate (not CO2)? |
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Definition
| in the cytosol of leaf mesophyll cells |
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Term
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Definition
| allows for malate to be oxidized & decarboxylated to yield pyruvate & CO2 in bundle-sheath cells; NADP+ is reduced |
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Term
| pyruvate phosphate dikinase |
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Definition
| catalyzes the enzymatic reaction in which the pyruvate (formed by decarboxylation of malate in bundle-sheath cells) is transferred back to the mesophyll cells & converted to PEP |
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