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15 Cards in this Set
- Front
- Back
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Gluconeogenesis
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- pyruvate to glucose from noncarbohydrate sources
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When does gluconeogenesis happen?
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- when brain needs glucose
- between meals and longer fasts - during vigorous exercise - when glycogen is depleted |
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What reactions of glycolysis are irreversible?
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1.) glucose -> G6P by hexokinase
2.) F6P -> F16BP by PFK-1 3.) PEP -> pyruv by pyruv kinase |
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Conversion of Pyruvate to Phosphoenolpyruvate
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- 1st bypass
- requires 2 exergonic rxn - Pyruvate turns into Oxaloacetate by Pyruvate carboxylase in the mitochondria - needs 2 ATP |
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How does Oxaloacetate go back to the cytosol from the mitochondria?
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- mitoch has no transporter for Oxaloacetate
- Oxaloacetate must be reduced to malate by malate dehydrogenase at the expense of NADH - malate leaves mito and reoxidized to Oxaloacetate also making NADH |
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Oxaloacetate is converted to PEP by what enzyme?
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Phosphoenolpyruvate carboxykinase and needs 2 GTP to form the high-energy cpd
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How does Lactate turn into PEP?
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- lactate from glycolysis in anaerobic
- lactate to pyruvate by lactate dehydrogenase making NADH - pyruvate goes to mitoch and turns into Oxaloacetate by Pyruv carboxylase - Oxalo turns to PEP in the mitoch by mitoch PEP carboxykinase - PEP goes out to gluconeogenesis |
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Conversion of Fructose 1,6-Bisphosphate to what in gluconeogenesis?
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- F16BP -> F6P
- 2nd bypass - catalyzed by Fructose 1,6-bisphosphatase (FBPase-1) - an irreversible hydrolysis of the C-1 phosphate |
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Conversion of Glucose 6-Phosphate to what in gluconeogenesis?
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- G6P to glucose
- 3rd bypass - dephosphorylation of G6P - catalyzed by Glucose 6-phosphatase - hydrolysis of phophate ester |
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What is required for gluconeogenesis of 1 glucose?
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- 2 pyruvate
- 4 ATP and 2 GTP - 2 NADH |
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Can animals convert acetyl-CoA derived from FAs into glucose?
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No, plants can
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Pentose phosphate pathway
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- G6P to ribose 5-phosphate and NADPH
- G6P -> lactone by G6P dehydrogenase making NADPH - lactone -> 6-phosphogluconate by lactonse - gluconate -> ribose 5-phosphate by 6-phosphogluconate dehydrogenase making NADPH |
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What are the pentoses used for?
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to make RNA and DNA
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What are NADPH use for?
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- reducing power to counter damaging effects of oxygen radicals
- to reduce oxidized glutathione (that was used to reduce peroxide which was from free radicals) |
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How can pentose phosphates be recycled back into glucose 6-phosphate?
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- through a nonoxidative phase
- six 5C sugar phosphates are turned in five 6C sugar phosphates - allowing continued oxidation of G6P and making more NADPH |
