The Glycoloysis Pathway
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| show | Glycolysis is one of the principal pathways for ATP generation in the brain and erythrocytes. It can generate ATP in the presence or absence of Oxygen as well as in the presence or absence of Mitochondria.
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| What is the major dietary source of glucose? | show 🗑
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| show | Glucose in the bloodstream enters cells via specific transporters (GLUT) by facilitated diffusion.
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| show | Neurons and Brain
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| Where is GLUT 2 found? | show 🗑
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| Where is GLUT 4 found and what is it responsive to? | show 🗑
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| show | 3 reactions.
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| show | Glucokinase is only found in the liver. It has a very high Km for glucose but is only activated when blood glucose levels are high.
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| show | Hexokinase is found in all tissues except the liver. It has a lower Km for glucose but is active all the time, independent of blood glucose levels.
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| show | Hereditary Diabetes Mellitus, glucose is unable to enter the liver which results in hypoglycemia.
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| What are the 3 possible fates of Glucose-6-phosphate in the liver? | show 🗑
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| What determines the fate of Glucose-6-phosphate in the liver? | show 🗑
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| In what part of the cell are the glycolytic enzymes located? | show 🗑
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| show | Stage 1 is the energy investment stage, Stage 2 is the cleavage of 6C sugar into 3C intermediates, and Stage 3 is the energy generation phase.
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| Describe Phase 1, the energy investment phase, of glycolysis. | show 🗑
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| show | Glucose is coverted to Glucose-6-Phosphate by Hexokinase or Glucokinase. This step uses 1 ATP and as such, it is irreversible/regulated.
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| What is the intermediate reaction in phase 1 of glycolysis? | show 🗑
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| What type of enzyme is Phosphoglucose isomerase? | show 🗑
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| What is the second phosphorylation reaction of phase 1 of glycolysis? | show 🗑
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| What is the MOST important step of the whole glycolysis pathway? | show 🗑
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| show | Fructose-1,6-bisphosphate is converted into two trioses via the enzyme Aldolase A. The trioses are Glyceraldehyde-3-phosphate and Dihydroxyacetone phosphate.
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| show | Dihydroxyacetone phosphate is coverted into another molecule of Glyceraldehyde-3-phosphate via Triosephosphate isomerase. So, the net gain from phase 2 of glycolysis is 2 molecules of Glyceraldehyde-3-phosphate.
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| Does phase 2 of glycolysis require energy (ATP)? | show 🗑
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| Describe the first reaction of phase 3 of glycolysis. | show 🗑
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| show | Arsenate. Arsenate can prevent the formation of 1,3-bisphosphoglycerate via Glyceraldehyde-3-phosphate dehydrogenase.
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| show | 2 reactions.
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| show | 1,3-bisphosphoglycerate is converted to 3-phosphoglyerate via phosphoglycerate kinase. This step generates 1 ATP via substrate level phosphorylation (without ETC or Mitochondria) and occures twice because of 2 molecules of 1,3-bisphosphoglycerate.
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| Is 1,3-bisphosphoglycerate a low energy compound? | show 🗑
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| When is the first ATP generated in the glycolysis pathway? | show 🗑
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| show | 3-phosphoglycerate is converted to 2-phosphoglycerate via phosphoglycerate mutase. This moves the phosphate from carbon 3 to carbon 2. This occurs twice because of 2 molecules of 3-phosphoglycerate.
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| Are the first 4 reactions in phase 3 of glycolysis reversible. | show 🗑
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| show | 2-phosphoglycerate is converted to phosphoenol pyruvate by the enzyme Enolase. This reactions creates 1 ATP via substrate level phophorylation (without ETC or mitochondria). It occurs twice because of 2 molecules of 2-phosphoglycerate.
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| show | There are 5 reactions, 4 reversible and 1 irreversible.
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| show | Floride.
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| Is Phosphoenol pyruvate a high energy compound? | show 🗑
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| show | Phosphoenol pyruvate is converted to pyruvate via pyruvate kinase. This creates 1 molcule of ATP via substrate level phosphorylation (with ETC or mitochondria). This step is irreversible and occurs twice because of 2 molecules of phosphoenol pyruvate.
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| Which step of phase 3 of glycolysis is irreversible? | show 🗑
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| show |
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| How many molecules of pyruvate are generated from one molecule of glucose via glycolysis? | show 🗑
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| How many carbons does pyruvate have? | show 🗑
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| show | 2 ATP are formed by the conversion of glucose to pyruvates via anaerobic glycolysis. Technically 4 ATP are formed but 2 are needed to fuel the cycle so the net gain is only 2 ATP.
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| What are the three possible fates of pyruvate? | show 🗑
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| What happens to Acetyl CoA? | show 🗑
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| show | It goes to the liver where it enters the Cori cycle.
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| What happens to NADH when Pyruvate is converted to Lactate? | show 🗑
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| Is the NADH/NAD+ reaction reversible? | show 🗑
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| How is Lactate (Lactic Acid) related to exercise? | show 🗑
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| show | This condition typically occurs during exercise when white skeletal muscle is actively contracting. The conversion of Pyruvate to Lactate is favored.
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| show | Cardiac muscle has a low NADH/NAD+ ratio and is predominantly aerobic due to high concentrations of mitochondria. The glycolysis that occurs anaerobically creates lactate, which cardiac mitochondria covert back then to Acetyl CoA to enter the TCA cycle.
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| show | Glucose is converted to 2 molecules of pyruvate via glycolysis, then to 2 molecules of Lactate. Lactate is then transported to the liver to be converted back to pyruvate and then to glucose (with addition of 6 ATP) to return to RBCs/skeletal muscle.
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| show | No, it must be transported to the liver/hepatocytes.
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| Which enzymes mediate the three irreversible reactions in glycolysis and which is most important? | show 🗑
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| show | Phosphoglycerate kinase and pyruvate kinase
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| show | In aerobic glycolysis, glucose is converted to 2 molecules of pyruvate, forming 2 molecules of NADH in the process. Each NADH yields 3 ATP each, for a total combined contribution of 6 ATP.
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| show | 10 ATP are created (4 from glucose conversion to pyruvates in glycolysis and 6 from NADH) but 2 are needed to fuel the cycle so the net gain is only 8 ATP.
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| Where is NADH converted to form ATP? | show 🗑
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| show | The first step of phase 1 of glycolysis using glucokinase/hexokinase, and the third step of phase 1, using Phosphofructokinase 1 (PFK1).
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| Why is fluoride added to tubes that will be used for estimation of blood glucose in the lab? | show 🗑
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| What is the significance of glycolysis in adipose tissue? | show 🗑
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| What is the significance of glycolysis in Red Blood Cells? | show 🗑
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| How does 2,3-BPG affect Hemoglobin’s affinity of oxygen? | show 🗑
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| show | RBC’s rely solely upon glycolysis for ATP. ATP is needed to maintain the electrolyte gradient (operated by Na+/K+ Pump) to maintain cell membrane. Defective glycolysis causes ATP deficiency which ruins the electrolyte gradient and membrane causing lysis.
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| Deficiency of which enzymes results in hemolytic anemia? | show 🗑
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| What happens to 2,3-BPG levels in pyruvate kinase deficient RBCs? | show 🗑
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| show | 2,3-BPG levels are DECREASED.
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| show | Erythrocytes (for ATP and 2,3-BPG), Brains (requires glycolysis during the fasting state), Actively contracting skeletal muscle (for glycolytic fiber function), Retina/Lens (for ATP), and Tumor Cells (for ATP).
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| show | Lactic Acidosis is an example of metabolic acidosis which occurs when pH is decreased, pCO2 is decreased, and HCO3- is decreased (in the compensated stage).
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| What are the 6 conditions under which Lactic Acidosis is observed? | show 🗑
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| Describe the ‘Warburg Effect’. | show 🗑
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| Describe metabolic changes in cancer. | show 🗑
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| show | A glucose analog called Fluorodeoxyglucose (FDG) is used for PET. Tumor cells preferentially utilize FDG causing an uptake of FDG by the tumor allowing them to be visualized on the scan. Glycolysis inhibitors are being explored as therapeutic agents.
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| Name two stimulators of glycolysis. | show 🗑
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| show | 1) Increase in ATP levels (due to energy excess in the resting state) and 2) Decreased Fructose-2,6-bisphophate levels (due to low blood glucose levels
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| Which step of glycolysis is inhibited by Arsenate? | show 🗑
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| Which step of glycolysis is inhibited by Fluoride? | show 🗑
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| At which steps is ATP used? | show 🗑
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| show | 1,3BPG to 3-phosphoglycerate via phosphoglycerate kinase, Phosphoenolpyruvate to pyruvate via pyruvate kinase
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| At which step is NAD+ used and NADH made? | show 🗑
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Created by:
sprater16