3500Ch16 - Fates of Glucose What happens when there is more/less glucose than is needed In times of plenty it can be stored as glycogen In some

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Fates of Glucose What happens when there is more/less glucose than is needed? In times of plenty it can be stored as glycogen In some tissues it can be diverted to create ribose-5- phosphate and NADPH In times of need glucose can be made from smaller precursors
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16 Gluconeogenesis Some tissues require glucose for function (i.e. brain and red blood cells) Liver and kidney produce glucose from noncarbohydrate precursors Under fasting conditions (within 16-24 hours of the last meal), gluconeogenesis is activated 2 Pyruvate + 2 NADH + 4 ATP + 2 GTP + 6 H2O + 2 H+ Glucose + 2 NAD+ + 4 ADP + 2 GDP + 6 Pi
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Major non-carbohydrate precursors Lactate Formed by active skeletal muscle Converted back to pyruvate by lactate dehydrogenase Amino acids Obtained from the diet Or during starvation from the wasting of skeletal muscle Triacylglycerols - the glycerol part
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Formation of DHAP from glycerol
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Gluconeogensis from Glycerol
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Where does gluconeogenesis occur? Liver Kidney Very little occurs in the brain, skeletal muscle, or heart muscle. The liver and kidney modulate glucose levels in the blood so that these other organs have enough.
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Gluconeogenesis is not glycolysis in reverse! Several reactions differ. Which ones? The metabolically irreversible ones! Hexokinase Phosphofructokinase Pyruvate kinase
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The three steps that change are the regulated steps! Gluconeogenesis versus Glycolysis
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1. Pyruvate carboxylase (PK) Catalyzes a metabolically irreversible reaction This reaction takes place in the mitochondria. Pyruvate + CO2+ ATP + H2O oxaloacetate + ADP + Pi + H+ Since we need 2 pyruvate for 1 glucose, this counts as 2 ATP used
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Domain structure of pyruvate carboxylase The biotin-binding domain is utilized to
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This note was uploaded on 02/03/2011 for the course CHEM 3500 taught by Professor Staff during the Spring '08 term at Kennesaw.

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3500Ch16 - Fates of Glucose What happens when there is more/less glucose than is needed In times of plenty it can be stored as glycogen In some

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