Term
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Definition
| the synthesis of glucose from noncarboydrate precursors |
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Term
| why it's important to maintain glucose levels |
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Definition
| because red blood cells need it and the brain uses it as its only fuel source |
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Term
| the part of the body that needs most of the glucose |
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Definition
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Term
| when gng is especially important |
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Definition
| during fasting or starvation |
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Term
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Definition
| mostly liver with small amount occurring in kidney |
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Term
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Definition
| helps maintain blood glucose so tissues that need it can access it |
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Term
| the gng pathway converts ______ into ______ |
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Definition
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Term
| the major noncarbohydrate precursors that get involved in gng |
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Definition
-lactate
-amino acids
-glycerol |
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Term
| how glycerol may enter the gng pathway |
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Definition
| by conversion of glycerol to dihydroxyacetone phosphate |
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Term
| depiction of the conversion of glycerol to dihydroxyacetone phosphate |
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Definition
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Term
| is gng a complete reversal of glycolysis? |
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Definition
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Term
| why is gng not a complete reversal of glycolysis? |
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Definition
| because the free energy of glycolysis is -90 kJ/mol, making it irreversible and necessary for gng to bypass the irreversible steps |
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Term
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Definition
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Term
| the conversion of pyruvate into phosphoenolpyruvate begins with... |
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Definition
| the formation of oxaloacetate |
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Term
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Definition
| carboxylation of pyruvate to form oxaloacetate |
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Term
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Definition
| enyme that catalyzes the carboxylation of pyruvate to form oxaloacetate |
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Term
| where the carboxylation of pyruvate to form oxaloacetate occurs |
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Definition
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Term
| depiction of the carboxylation of pyruvate to form oxaloacetate |
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Definition
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Term
| importance of biotin to pyruvate carboxylase |
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Definition
| biotin is a covalently attached prosthetic group that serves as the carrier of activated CO2 |
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Term
| the 3 stages of pyruvate carboxylation |
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Definition
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Term
| how oxaloacetate is processed in the mitochondria |
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Definition
in matrix: pyruvate --> oxaloacetate --> malate
in cytoplasm: malate --> oxaloacetate |
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Term
| depiction of how oxaloacetate is processed in the mitochondria |
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Definition
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Term
| phosphoenolpyruvate carboxykinase (PEPCK) |
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Definition
| catalyzes the decarboxylation and phosphorylation of of oxaloiacetate |
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Term
| depiction of the function of phosphoenolpyruvate carboxykinase (PEPCK) |
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Definition
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Term
| the sum of the rxns catalyzed by pyruvate carboxylase and phosphoenolpyruvate carboxylase |
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Definition
| pyruvate + ATP + GTP + H2O --> phosphoenolpyruvate + ADP + GDP + Pi + 2 H+ |
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Term
| importance of decarboxylation |
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Definition
| often drives rxns that are otherwise highly endergonic |
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Term
| fructose 1,6-bisphosphotase |
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Definition
| catalyzes conversion of fructose 1,6-bisphosphate to fructose 6-phosphate |
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Term
| depiction of the function of fructose 1,6-bisphosphotase |
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Definition
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Term
| where gng ends in most tissues |
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Definition
| conversion of fructose 6-phosphate into glucose 6-phosphate, which is often stored as glycogen |
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Term
| where the final step in the generation of free glucose occurs |
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Definition
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Term
| metabolic duty of the liver |
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Definition
| to maintain adequate levels of glucose in the blood for use by other organs |
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Term
| how glucose 6-phosphate gets converted to free glucose |
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Definition
| transported into lumen of endoplasmic reticulum, where it is hydrolyzed to glucose by glucose 6-phosphatase, which is bound to the ER membrane.
glucose and Pi are then shuttled out into the cytoplasm by transporters |
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Term
| depiction of generation of glucose from glucose 6-phosphate |
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Definition
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Term
| the NTP difference between glycolysis and gng |
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Definition
| glycolysis yields 2 ATP while gng requires 4 ATP and 2 GTP (6 NTP) |
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Term
| when glycolysis predominates |
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Definition
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Term
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Definition
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Term
| what determines whether glycolysis or gng will be more active? |
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Definition
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Term
| the key regulation site in the gng pathway |
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Definition
| the interconversion of fructose 6-phosphate and fructose 1,6-bisphosphate |
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Term
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Definition
| seems to be ratio of ATP/AMP |
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Term
| something indicated by high AMP concentration |
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Definition
| energy is needed, thus stimulating glycolysis and inhibiting gng |
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Term
| something indicated by high ATP concentration |
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Definition
| the energy charge is high and biosynthetic intermediates are abundant, thus inhibiting glycolysis |
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Term
| something indicated by high citrate concentration |
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Definition
| reports the status of the citric acid cycle; high citrate indicates energy rich situation and precursors for biosynthesis, inhibiting glycolysis and stimulating gng |
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Term
| where the interconversion of phosphoenolpyruvate and pyruvate occurs |
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Definition
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Term
| something indicated by high alanine concentration |
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Definition
| energy charge is hidh and building blocks are abundant, inhibiting pyruvate kinase in glycolysis |
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Term
| depiction of the reciprocal regulation of glycolysis and gng in the liver |
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Definition
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Term
| phosphofructokinase 2 (PFK2) |
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Definition
| catalyzes the conversion of fructose 6-phosphate to fructose 2,6-bisphosphate |
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Term
| fructose bisphosphatase 2 (FBPase2) |
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Definition
| catalyzes conversion of fructose 2,6-bisphosphate to frucose 6-phosphate |
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Term
| something striking about PFK2 and FBPase2 |
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Definition
| they're both in a single 55-kDa polypeptide chain; it's a bifunctional enzyme |
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Term
| composition of the bifunctional PFK2/FBPase2 enzyme |
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Definition
| N-terminal regulatory domain followed by a kinase domain and a phosphatase domain |
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Term
| how it is determined whether a bifunctional PFK2/FBPase2 enzyme functions as PFK2 or FBPase2 |
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Definition
| the activities of PFK2 and FBPase2 are reciprocally controlled by the phosphorylation of a single serine residue |
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Term
| when the bifunctional PFK2/FBPase2 enzyme functions as FBPase2 |
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Definition
when blood glucose is low
gng predominates |
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Term
| how low blood glucose causes the bifunctional PFK2/FBPase2 enzyme to act as FBPase2 |
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Definition
| when glucose in scarce, blood glucagon rises and triggers a cyclic AMP signal cascade, leading to the phospkorylation of this enzyme by protein kinase A; this activates FBPase2 and inhibits PFK2 |
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Term
| when the bifunctional PFK2/FBPase2 enzyme functions as PFK2 |
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Definition
when blood glucose is high
glycolysis predominates |
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Term
| how high blood glucose causes the bifunctional PFK2/FBPase2 enzyme to act as PFK2 |
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Definition
| glucagon falls and insulin rises, causing the phosphoryl group to be removed; this activates PFK2 and inhibits FBPase2 |
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Term
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Definition
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Term
| depiction of the bifunctional PFK2/FBPase2 enzyme |
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Definition
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Term
| depiction of the control of the synthesis and degradation of fructose 2,6-bisphosphate |
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Definition
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Term
| what lets contracting skeletal muscle generate ATP in the absence of oxygen? |
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Definition
| the formation and release of lactate |
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Term
| 2 possible fates of lactate |
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Definition
1: diffuses into cardiac and slow-twitch (type 1) muscle to be reverted to pyruvate to be metabolized thru the citric acid cycle and oxidative phosphorylation to generate ATP
2: excess lactate enters the liver to be converted into pyruvate, then to glucose by the gng pathway |
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Term
| what the liver does for active muscles |
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Definition
| restores the levels of glucose needed for active muscle cells, which derive ATP from the conversion of glucose into lactate |
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Term
| depiction of a substrate cycle |
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Definition
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Term
| depiction of the Cori cycle |
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Definition
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Term
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Definition
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