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Questions and Answers
What is the product of anaerobic glycolysis when pyruvate is converted?
What is the product of anaerobic glycolysis when pyruvate is converted?
Which enzyme is responsible for converting lactose into glucose and galactose?
Which enzyme is responsible for converting lactose into glucose and galactose?
What is the primary driving force behind the conversion of lactate to pyruvate in glycolysis?
What is the primary driving force behind the conversion of lactate to pyruvate in glycolysis?
What is a notable characteristic of the enzyme lactate dehydrogenase (LDH)?
What is a notable characteristic of the enzyme lactate dehydrogenase (LDH)?
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Which carbohydrate is primarily broken down by amylases?
Which carbohydrate is primarily broken down by amylases?
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What is the primary pathway for fructose metabolism in the liver?
What is the primary pathway for fructose metabolism in the liver?
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Which of the following glycolytic intermediates is NOT produced from the catabolism of non-glucose carbohydrates?
Which of the following glycolytic intermediates is NOT produced from the catabolism of non-glucose carbohydrates?
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What metabolic condition is primarily addressed by gluconeogenesis?
What metabolic condition is primarily addressed by gluconeogenesis?
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Which enzyme is involved in the conversion of galactose as part of the Leloir pathway?
Which enzyme is involved in the conversion of galactose as part of the Leloir pathway?
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What is one significant consequence of a genetic disorder affecting step 2 of galactose metabolism?
What is one significant consequence of a genetic disorder affecting step 2 of galactose metabolism?
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What is the primary purpose of replenishing cytosolic NAD+ in the glycolytic process?
What is the primary purpose of replenishing cytosolic NAD+ in the glycolytic process?
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How is NAD+ regenerated in anaerobic glycolysis?
How is NAD+ regenerated in anaerobic glycolysis?
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Which statement best describes the malate-aspartate shuttle?
Which statement best describes the malate-aspartate shuttle?
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What is the theoretical maximum ATP yield from anaerobic glycolysis?
What is the theoretical maximum ATP yield from anaerobic glycolysis?
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What affects the actual ATP yield from oxidative phosphorylation?
What affects the actual ATP yield from oxidative phosphorylation?
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Which factor primarily drives lactate dehydrogenase in the cytosol?
Which factor primarily drives lactate dehydrogenase in the cytosol?
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Which of the following statements accurately describes anaerobic glycolysis?
Which of the following statements accurately describes anaerobic glycolysis?
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Which shuttle is used when NADH cannot cross the mitochondrial membrane?
Which shuttle is used when NADH cannot cross the mitochondrial membrane?
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What is the main location of glycolysis within a cell?
What is the main location of glycolysis within a cell?
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Which enzyme is responsible for the phosphorylation of glucose to glucose-6-phosphate in the activation phase of glycolysis?
Which enzyme is responsible for the phosphorylation of glucose to glucose-6-phosphate in the activation phase of glycolysis?
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What is the net energy yield per molecule of glucose in glycolysis?
What is the net energy yield per molecule of glucose in glycolysis?
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During glycolysis, what is the significance of glucose-6-phosphate being negatively charged?
During glycolysis, what is the significance of glucose-6-phosphate being negatively charged?
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Which of the following describes a key aspect of the energy investment phase of glycolysis?
Which of the following describes a key aspect of the energy investment phase of glycolysis?
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How many enzymes are involved in the cleavage of glucose-6-phosphate in glycolysis?
How many enzymes are involved in the cleavage of glucose-6-phosphate in glycolysis?
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What are the end products of glycolysis from one mole of glucose?
What are the end products of glycolysis from one mole of glucose?
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Which enzyme is involved in converting glucose-6-phosphate to fructose-6-phosphate?
Which enzyme is involved in converting glucose-6-phosphate to fructose-6-phosphate?
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What is the primary reason for the structural design of glycogen?
What is the primary reason for the structural design of glycogen?
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Which organs are primarily responsible for glycogen metabolism?
Which organs are primarily responsible for glycogen metabolism?
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What is true regarding glycogen catabolism and anabolism?
What is true regarding glycogen catabolism and anabolism?
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In what situation is glycogenolysis predominantly activated?
In what situation is glycogenolysis predominantly activated?
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What does low oxygen availability signal in the context of glycogen metabolism?
What does low oxygen availability signal in the context of glycogen metabolism?
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Which metabolic fuel is primarily used by the brain?
Which metabolic fuel is primarily used by the brain?
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During fasting, how long does glycogen last before it is depleted?
During fasting, how long does glycogen last before it is depleted?
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Which of the following pathways does NOT contribute to gluconeogenesis?
Which of the following pathways does NOT contribute to gluconeogenesis?
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What is a major source of reducing power for biosynthetic processes?
What is a major source of reducing power for biosynthetic processes?
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Which enzyme is used in gluconeogenesis instead of pyruvate kinase from glycolysis?
Which enzyme is used in gluconeogenesis instead of pyruvate kinase from glycolysis?
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Which organ is primarily responsible for gluconeogenesis during fasting?
Which organ is primarily responsible for gluconeogenesis during fasting?
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What process converts lactate released from muscles into glucose in the liver?
What process converts lactate released from muscles into glucose in the liver?
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Which step in glycolysis cannot be simply reversed in gluconeogenesis?
Which step in glycolysis cannot be simply reversed in gluconeogenesis?
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What does the pentose phosphate pathway primarily provide in terms of metabolic function?
What does the pentose phosphate pathway primarily provide in terms of metabolic function?
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Which of the following compounds is NOT a substrate for gluconeogenesis?
Which of the following compounds is NOT a substrate for gluconeogenesis?
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Which enzyme involved in gluconeogenesis converts fructose-1,6-bisphosphate back to fructose-6-phosphate?
Which enzyme involved in gluconeogenesis converts fructose-1,6-bisphosphate back to fructose-6-phosphate?
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What is the primary role of the pentose phosphate pathway?
What is the primary role of the pentose phosphate pathway?
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What byproduct does the pentose phosphate pathway generate alongside ribonucleosides?
What byproduct does the pentose phosphate pathway generate alongside ribonucleosides?
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Which substrate does muscle convert to alanine for gluconeogenesis?
Which substrate does muscle convert to alanine for gluconeogenesis?
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Study Notes
Metabolism of Sugars
- This lecture covers the metabolism of sugars, including catabolism, anabolic pathways, regulatory concepts, and the Pentose Phosphate Pathway.
- The lecturer, Jane Carré, is a lecturer in Human Nutrition and Metabolism at the University of Plymouth.
- Recommended textbooks for additional study include Introduction to Nutrition and Metabolism by Bender and Cunningham (2021) and Introduction to Human Nutrition by Leverve (2011).
- Further depth can be gained from Biochemistry by Berg et al. (2023).
- Learning outcomes include key aspects of major metabolic pathways (Glycolysis, TCA cycle, Oxidative phosphorylation), macronutrient metabolism (CHO, fats, and protein), metabolic concepts (energetic conservation, driving forces in metabolism, catabolism & anabolism, the steady state, metabolic control).
Glycolysis
- Glycolysis is a 10-step process in the cytosol that converts one glucose molecule (6C) to two pyruvate molecules (3C).
- The location of glycolysis is the cytosol
- Results in energy yield: 2 ATP, 2 NADH.
- Consists of 3 phases: Activation, Cleavage, and Pay-off.
- Glycolysis involves 10 enzymatic reactions converting glucose to pyruvate.
- Important metabolites: glucose-6-phosphate, fructose-6-phosphate, fructose-1,6-bisphosphate, and pyruvate
- Key enzymes in glycolysis include hexokinase, phosphofructokinase, pyruvate kinase.
Glycolysis: Endpoints
- Glycolysis has two possible endpoints, depending on the metabolic fate of pyruvates.
- Anaerobic glycolysis results in the production of lactate.
- Aerobic glycolysis results in the production of acetyl CoA which enters the TCA cycle and oxidative phosphorylation.
Anaerobic Glycolysis
- The main enzyme driving anaerobic glycolysis is lactate dehydrogenase.
- This reaction is reversible.
- The driving force is the mass action of NADH/NAD+.
Aerobic Glycolysis
- NAD+ is regenerated during oxidative metabolism via metabolite shuttles.
- The process yields more ATP compared to anaerobic glycolysis.
Glycogen Metabolism
- Glycogen is the storage form of glucose.
- Glycogenolysis releases glucose for further metabolic processes, resulting in ATP production.
- Glycogenesis synthesizes glycogen from glucose.
- Key regulators include glucose, ATP, F-1,6-BP, etc.
Gluconeogenesis
- Gluconeogenesis is the process of de novo synthesis of glucose from non-carbohydrate sources in the liver, kidney cortex, and small intestine.
- Important substrates include amino acids (e.g., alanine), glycerol, and lactate.
- The pathway is largely a reversal of glycolysis, but three key steps differ.
- Regulation of gluconeogenesis is tightly controlled and involves distinct enzymes from those in glycolysis,
Pentose Phosphate Pathway
- The Pentose Phosphate Pathway is an alternative pathway for glucose-6-phosphate and forms NADPH and other necessary substances.
- NADPH is crucial for reductive biosynthesis like fatty acid synthesis.
- It also produces pentoses for nucleotide synthesis.
Other Dietary Carbohydrates
- Fructose, lactose, and sucrose are other sugars that are also processed and catabolised in the body.
Other Concepts
- Metabolic flexibility enables cells to adapt to different conditions by using diverse energy pathways.
- The slides also present learning outcomes, consolidation questions, reading materials, outlines for better study planning.
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Description
Test your knowledge on key concepts from biochemistry, focusing on glycolysis and carbohydrate metabolism. This quiz covers topics such as anaerobic glycolysis, enzyme functions, and the breakdown of carbohydrates. Challenge yourself with these essential questions.
