Term
| 2 conditions under which metabolism of glucose can occur |
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Definition
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Term
| How is metabolism of glucose different in the liver than in the muscles/brain? |
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Definition
liver = storage
muscles/brain = form ATP |
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Term
| What happens when there are high glucose levels? |
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Definition
| glucose entry into liver & pancreas |
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Term
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Definition
| energy by catabolism of glucose |
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Term
| Does glycolysis occur under aerobic or anaerobic conditions? |
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Definition
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Term
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Definition
| "preparatory phase"; energy invested to form activated sugars |
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Term
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Definition
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Term
| Is the reaction catalyzed by phosphohexose isomerase in glycolysis thermodynamically favorable or unfavorable? |
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Definition
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Term
| What is the major regulatory step of glycolysis? |
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Definition
| phosphofructokinase (PFK) catalyzing the 2nd phosphorylation step --> fructose 1,6-bisphosphate |
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Term
| What is the only product formed by aldolase that can continue on in glycolysis? |
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Definition
| glyceraldehyde 3-phosphate |
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Term
| What is the end of the prep phase of glycolysis? |
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Definition
| formation of 2 glyceraldehyde 3-phosphate molecules |
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Term
| What type of catalysis is used by glyceraldehyde 3-phosphate dehydrogenase to convert GAP to 1,3-bisphosphoglycerate in glycolysis? |
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Definition
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Term
| What mechanism does phosphoglycerate kinase (PGK) use to make ATP in glycolysis? |
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Definition
| substrate level phosphorylation |
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Term
| Does phosphoglycerate mutase create a molecule with a higher or lower energy potential in glycolysis? |
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Definition
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Term
| What type of reaction does enolase perform to make 2-PG --> PEP in glycolysis? |
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Definition
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Term
| What type of reaction is catalyzed by pyruvate kinase (PK) in glycolysis? |
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Definition
| the second substrate level phosphorylation |
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Term
| net reaction of glycolysis |
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Definition
| 1 glucose + 2 ADP + 2 Pi + 2 NAD+ --> 2 pyruvate + 2 ATP + 2 NADH + 2 H+ + 2 H2O |
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Term
| Cells oxidize pyruvate to generate ______. |
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Definition
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Term
| Under anaerobic conditions, animal tissues undergo ______ to regenerate NAD+. |
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Definition
| fermentation of pyruvate --> lactate |
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Term
| What must happen to dietary sugars in order for them to by metabolized? |
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Definition
| they must be converted to glucose or glycolysis intermediates |
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Term
| What is the role of glycolysis in muscle? |
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Definition
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Term
| How many steps are there at which glycolysis is regulated in muscle? |
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Definition
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Term
| How does hexokinase regulate glycolysis in muscle? |
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Definition
| allosterically inhibited by glucose 6-phosphate |
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Term
| What is the most important control site for glycolysis in muscle? |
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Definition
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Term
| When does PFK activity for glycolysis in muscle increase? |
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Definition
| when ATP/AMP ratio decreases |
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Term
| How does pyruvate kinase regulate glycolysis in muscle? |
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Definition
| allosterically inhibited by ATP |
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Term
| What is the point of glycolysis regulation in the liver? |
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Definition
| the liver works to maintain blood glucose levels |
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Term
| What is the primary enzyme for formation of glucose-6-phosphate in the liver? |
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Definition
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Term
| How does liver PFK regulate glycolysis? |
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Definition
| energy charge & citrate (the first product of the citric acid cycle) |
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Term
| How does liver pyruvate kinase regulate glycolysis? |
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Definition
| allosterically but also by covalent modification |
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Term
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Definition
| process of making new glucose from lactate, pyruvate, & non-carbohydrate precursors |
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Term
| How do you make gluconeogenesis favorable? |
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Definition
| counter exergonic (irreversible) glycolysis steps |
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Term
| How many steps does it take to convert pyruvate to PEP in gluconeogenesis? |
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Definition
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Term
| fructose-1,6-bisphosphatase (AKA FBP-ase1) (gluconeogenesis) |
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Definition
| catalyzes conversion of fructose-1,6-bisphosphate --> fructose-6-phosphate |
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Term
| glucose-6-phosphate (gluconeogenesis) |
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Definition
| hydrolyzes glucose 6-phosphate to form glucose & orthophosphate (inorganic phosphate) |
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Term
| net reaction of gluconeogenesis |
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Definition
| 2 pyruvate + 4 ATP + 2 GTP + 2 NADH + 4 H2O --> glucose + 4 ADP + 2 GDP + 6 Pi + 2 NAD+ + 2H+ |
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Term
| When do glycolysis & gluconeogenesis work together? |
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Definition
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Term
| What is the final product of glycolysis? |
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Definition
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Term
| What catalyzes the conversion of pyruvate --> acetyl-CoA? |
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Definition
| pyruvate dehydrogenase complex |
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Term
| 3 enzyme components for PDH complex |
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Definition
1. E1
2. E2 (a trimer)
3. E3 (a dimer) |
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Term
| 6 step reaction sequence for the PDH complex |
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Definition
1. pyruvate binds covalently to TPP cofactor of E1 & becomes decarboxylated
2. E1 transfers hydroxyethyl group from E1 to lipoamide cofactor
3. lipoamide arm with thioacetate swings into active site of E2
4. E2 transfers acetyl group from lipoamide --> coenzyme A
5. E3 oxidizes lipoamide of E2
6. E3 oxidizes FADH2 |
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