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40 Cards in this Set
- Front
- Back
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What is the MAJOR gluconeogenic organ?
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Liver
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What is biosynthesis of new glucose?
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Gluconeogenesis (definition)
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Is gluconeogenesis considered a fast or slow response?
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Slow ( up to 18 hrs to become primary source)
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What 3 metabolites in the liver become glucose in the starved state and fasted state?
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Glycerol
Amino acids lactate |
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What are the three glycolytic enzymes in gluconeogenesis?
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1. Pyruvate kinase
2. PFK-1 3. Hexo/gluco kinase |
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What is Pyruvate Kinase activated by?
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Fructose 1,6 bisphosphate
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What is Pyruvate Kinase inhibited by?
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ATP and phosphorylation (glucagons & E increase PKA)
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What is PFK-1 activated by?
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Activated by Fructose 2,6 bisphosphate, AMP
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What is PFK-1 inhibited by?
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Inhibited by – ATP and Citrate
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What is Glucokinase induced by?
Km? |
Induced by insulin
High Km for glucose |
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What are the 4 gluconeogenic enzymes that bypass the steps?
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1. Pyruvate carboxylase
2. Phosphoenolpyruvate carboxykinase (PEP CK) 3. Fructose 1,6 bisphosphatase 4. Glucose 6-phosphatase |
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What is Pyruvate carboxylase activated by?
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Acetyl CoA
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What is PEPCK induced by? Repressed by?
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Induced by glucagons, E, glucocorticoids
Repressed by: insulin |
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What is Fructose 1,6 bisphosphate inhibited by? Induced by?
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Inhibited by: F-2,6-bisP and AMP
Induced by: fasting |
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What is Glucose 6-phosphatase induced by?
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Induced during fasting
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What two things are required for the formation of the backbone of the glucose molecule during gluconeogenesis?
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1. Source of energy
2. Source of carbons |
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What are the three primary sources for carbon skeletons?
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Lactate – produced during anerobic glycolysis
Amino Acids – derived from muscle protein Glycerol- from triglycerides during lipolysis |
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What are the two enzymes involved in the conversion of pyruvate to Phosphoenolpyruvate (PEP) Bypass-1?
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Mitochondrial Pyruvate carboxylase (ATP required)
PEP carboxykinase (PEPCK) |
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What enzyme catalyzes (by hydrolysis) the conversion of Fructose 1,6 Bisphosphate to Frutose -6- phosphate? (bypass 2)
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Fructose 1, 6 bisphosphatase (F1,6BPase)
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What enzyme is responsible for the conversion of Glucose-6-phosphate (G6P) to Glucose (or glycogen) ? bypass 3
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Glucose-6-phosphatase G6Pase
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What is the predominant source of carbon atoms for glucose synthesis by gluconeogenesis?
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Lactate
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What is the enzyme responsible for the conversion of pyruvate to lactate during anaerobic glycolysis in red blood cells and skeletal muscle?
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Lactate Dehydrogenase (LDH)
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PEPCK requires ______ in the decarboxylation of OAA to form PEP?
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GTP
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What is the path of the cori cycle?
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Lactate > bloodstream > liver > glucose > blood > replenish glycogen stores in muscle.
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When the glycogen stores are depleted: what is used to maintain blood glucose levels?
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Amino acids – obtained by the catabolism of muscle proteins (source of carbon)
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What are the two amino acids that are not considered glucogenic?
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Leucine
lysine |
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When amino acids are glucogenic what happens to them to convert them to glucose?
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Deamination of their carbon skeletons.
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What are the two major amino acids that are transported from the muscle to form pyruvate?
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alanine and glutamine
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What is Alanine directly converted to?
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Pyruvate
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What is Alanine directly converted to?
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α-ketoglutarate
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Aspartate can be converted to what?
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OAA
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What part of a lipid can be used for gluconeogenesis?
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Glycerol backbone
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What phosphorylation reaction has to take place for glycerol to be used in gluconeogenesis?
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Glycerol is phosphorylated to glycerol-3-phosphate by glycerol kinase
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What enzyme is used in the dehydrogenation of glycerol to DHAP?
(through glycerol-3-phosphate) |
glycerol-3-phosphate dehydrogenase
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Adipose cells lack what enzyme?
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glycerol kinase
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What TCA-intermediate is propionyl-CoA converted to?
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Succinyl-CoA
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All enzymes involved in ethanol metabolism are?
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Isozymes
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Enzyme glucose 6-phosphatase is found in what organelle?
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ER
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Alcohol dehydrogenase
A. uses NAD B. uses NADPH C. oxidizes ethanol to acetate |
A. uses NAD
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Ethanol is reduced to acetaldehyde by what enzyme?
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Alcohol dehydrogenase (ADH)
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