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Questions and Answers
What is the yield of ATP from the oxidation of β-hydroxybutyrate?
What is the yield of ATP from the oxidation of β-hydroxybutyrate?
- 22 ATP
- 19 ATP
- 21.5 ATP (correct)
- 17 ATP
Which factor primarily regulates ketolysis?
Which factor primarily regulates ketolysis?
- Availability of fatty acids
- Availability of oxaloacetate (correct)
- Insulin levels
- Glucose concentration
What adaptation occurs in the brain during starvation after 5-6 days?
What adaptation occurs in the brain during starvation after 5-6 days?
- Increased fatty acid oxidation
- Increased glucose utilization
- Adaptation to using ketone bodies (correct)
- Decreased energy requirements
Which condition is NOT a cause of ketosis?
Which condition is NOT a cause of ketosis?
What is the normal range of ketone bodies in blood?
What is the normal range of ketone bodies in blood?
What is the key enzyme involved in cholesterol synthesis?
What is the key enzyme involved in cholesterol synthesis?
What happens to HMG-CoA reductase when insulin is present?
What happens to HMG-CoA reductase when insulin is present?
Which hormone acts as a repressor of HMG-CoA reductase?
Which hormone acts as a repressor of HMG-CoA reductase?
During periods of low energy availability, cholesterol synthesis is affected how?
During periods of low energy availability, cholesterol synthesis is affected how?
What mechanism do statins use to lower plasma cholesterol?
What mechanism do statins use to lower plasma cholesterol?
What is the primary enzyme responsible for synthesizing glycerol-3-phosphate in the liver and kidneys?
What is the primary enzyme responsible for synthesizing glycerol-3-phosphate in the liver and kidneys?
Which tissue synthesizes glycerol-3-phosphate by reducing dihydroxyacetone phosphate (DHAP)?
Which tissue synthesizes glycerol-3-phosphate by reducing dihydroxyacetone phosphate (DHAP)?
What is the first product formed when glycerol-3-phosphate condenses with two acyl-CoA molecules?
What is the first product formed when glycerol-3-phosphate condenses with two acyl-CoA molecules?
Which enzyme is involved in removing phosphate from phosphatidic acid to form diacylglycerol?
Which enzyme is involved in removing phosphate from phosphatidic acid to form diacylglycerol?
What final product is produced after the esterification of diacylglycerol with an additional acyl-CoA molecule?
What final product is produced after the esterification of diacylglycerol with an additional acyl-CoA molecule?
What is the active form of Acetyl-CoA Carboxylase (ACC)?
What is the active form of Acetyl-CoA Carboxylase (ACC)?
Which of the following hormones is responsible for inhibiting lipogenesis?
Which of the following hormones is responsible for inhibiting lipogenesis?
Which carbon source is used by the microsomal system for fatty acid elongation?
Which carbon source is used by the microsomal system for fatty acid elongation?
What is the role of cholesterol in the formation of cell membranes?
What is the role of cholesterol in the formation of cell membranes?
What distinguishes the microsomal system for fatty acid elongation from de novo synthesis?
What distinguishes the microsomal system for fatty acid elongation from de novo synthesis?
How is vitamin D3 synthesized from cholesterol?
How is vitamin D3 synthesized from cholesterol?
Which of the following fatty acids cannot be synthesized by the body?
Which of the following fatty acids cannot be synthesized by the body?
What are the steroid hormones derived from cholesterol?
What are the steroid hormones derived from cholesterol?
What proportion of cholesterol in plasma is present as cholesteryl esters?
What proportion of cholesterol in plasma is present as cholesteryl esters?
Which of the following is NOT a function of cholesterol?
Which of the following is NOT a function of cholesterol?
What is the primary cause of Refsum's Disease?
What is the primary cause of Refsum's Disease?
In which tissues does phytanic acid accumulate due to a deficiency of α-hydroxylase?
In which tissues does phytanic acid accumulate due to a deficiency of α-hydroxylase?
Which systems are responsible for fatty acid synthesis?
Which systems are responsible for fatty acid synthesis?
What is the initial substrate used for de novo fatty acid synthesis?
What is the initial substrate used for de novo fatty acid synthesis?
Where does the cytosolic system for de novo fatty acid synthesis primarily occur?
Where does the cytosolic system for de novo fatty acid synthesis primarily occur?
What occurs as a result of increased lipolysis during ketogenesis?
What occurs as a result of increased lipolysis during ketogenesis?
Where does ketolysis primarily occur?
Where does ketolysis primarily occur?
What is the primary consequence of increased ketogenesis in ketosis?
What is the primary consequence of increased ketogenesis in ketosis?
What is the role of succinyl-CoA in the process of ketolysis?
What is the role of succinyl-CoA in the process of ketolysis?
Which of the following substances is considered anti-ketogenic?
Which of the following substances is considered anti-ketogenic?
Which molecule is produced from the conversion of β-hydroxybutyrate during ketolysis?
Which molecule is produced from the conversion of β-hydroxybutyrate during ketolysis?
What is the maximum level of ketonemia considered physiological during a ketogenic diet?
What is the maximum level of ketonemia considered physiological during a ketogenic diet?
What happens to the Krebs cycle during increased ATP production from ketogenesis?
What happens to the Krebs cycle during increased ATP production from ketogenesis?
What is one of the main objectives of administering IV glucose during the management of ketosis?
What is one of the main objectives of administering IV glucose during the management of ketosis?
What happens to acetyl CoA when oxaloacetate is absent and ATP levels are high?
What happens to acetyl CoA when oxaloacetate is absent and ATP levels are high?
What is the initial substrate that combines with oxaloacetate to form citrate in the mitochondria?
What is the initial substrate that combines with oxaloacetate to form citrate in the mitochondria?
Which enzyme converts citrate back into oxaloacetate and acetyl-CoA in the cytosol?
Which enzyme converts citrate back into oxaloacetate and acetyl-CoA in the cytosol?
How many acetyl-CoA molecules are required for the synthesis of palmitic acid?
How many acetyl-CoA molecules are required for the synthesis of palmitic acid?
Which of the following statements is true about malonyl-CoA?
Which of the following statements is true about malonyl-CoA?
What is one source of NADPH used in fatty acid synthesis in the cytosol?
What is one source of NADPH used in fatty acid synthesis in the cytosol?
What is the primary source of acetyl CoA for ketogenesis?
What is the primary source of acetyl CoA for ketogenesis?
What is the first step in the ketogenesis process?
What is the first step in the ketogenesis process?
Where does ketogenesis primarily occur in the body?
Where does ketogenesis primarily occur in the body?
Which enzyme is responsible for the conversion of HMG-CoA to Acetoacetate?
Which enzyme is responsible for the conversion of HMG-CoA to Acetoacetate?
What is the terminal product of β-hydroxybutyrate oxidation?
What is the terminal product of β-hydroxybutyrate oxidation?
Which ketone body is produced from the spontaneous conversion of Acetoacetate?
Which ketone body is produced from the spontaneous conversion of Acetoacetate?
Which substrate is required for the conversion of Acetoacetate to β-hydroxybutyrate?
Which substrate is required for the conversion of Acetoacetate to β-hydroxybutyrate?
Which of the following is NOT a ketone body produced during ketogenesis?
Which of the following is NOT a ketone body produced during ketogenesis?
Flashcards
Cholesterol's role in cell membranes
Cholesterol's role in cell membranes
Cholesterol controls the flexibility of cell membranes.
Forms of cholesterol in lipoproteins
Forms of cholesterol in lipoproteins
Plasma lipoproteins carry cholesterol in two forms: free cholesterol in the outer layer and cholesterol esters inside the core.
Cholesterol's role in Vitamin D3 synthesis
Cholesterol's role in Vitamin D3 synthesis
Vitamin D3 is made from cholesterol through a series of steps involving sunlight exposure.
Cholesterol as a precursor for steroid hormones
Cholesterol as a precursor for steroid hormones
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Cholesterol's role in bile acid formation
Cholesterol's role in bile acid formation
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Ketosis
Ketosis
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Ketoacidosis
Ketoacidosis
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Ketogenesis
Ketogenesis
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Ketogenic Diet
Ketogenic Diet
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Physiological Ketosis
Physiological Ketosis
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What is HMG-CoA reductase?
What is HMG-CoA reductase?
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How does insulin and glucagon regulate HMG-CoA reductase?
How does insulin and glucagon regulate HMG-CoA reductase?
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How does cholesterol regulate its own synthesis?
How does cholesterol regulate its own synthesis?
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What is the role of AMPK in cholesterol synthesis?
What is the role of AMPK in cholesterol synthesis?
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How do statins work to lower cholesterol?
How do statins work to lower cholesterol?
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Acetyl-CoA Carboxylase (ACC)
Acetyl-CoA Carboxylase (ACC)
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Hormonal Regulation of Fatty Acid Synthesis: Excess Glucose
Hormonal Regulation of Fatty Acid Synthesis: Excess Glucose
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Hormonal Regulation of Fatty Acid Synthesis: Anti-insulin Hormones
Hormonal Regulation of Fatty Acid Synthesis: Anti-insulin Hormones
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Microsomal System for Fatty Acid Elongation
Microsomal System for Fatty Acid Elongation
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Essential Fatty Acids (EFA)
Essential Fatty Acids (EFA)
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Regulation of Ketolysis
Regulation of Ketolysis
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Importance of Ketone Bodies
Importance of Ketone Bodies
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Ketogenesis and Fatty Acid Oxidation
Ketogenesis and Fatty Acid Oxidation
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Glycerol kinase
Glycerol kinase
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Triacylglycerol
Triacylglycerol
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Dihydroxyacetone phosphate (DHAP)
Dihydroxyacetone phosphate (DHAP)
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Triacylglycerol synthesis (Esterification)
Triacylglycerol synthesis (Esterification)
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Phosphatidic acid (1,2-diacylglycerol-3-phosphate)
Phosphatidic acid (1,2-diacylglycerol-3-phosphate)
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What is ketogenesis?
What is ketogenesis?
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How does ketogenesis occur?
How does ketogenesis occur?
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What is ketolysis?
What is ketolysis?
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How does ketolysis depend on the Krebs cycle?
How does ketolysis depend on the Krebs cycle?
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What is the final product of ketolysis?
What is the final product of ketolysis?
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Where does ketogenesis occur?
Where does ketogenesis occur?
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What are the main ketone bodies?
What are the main ketone bodies?
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What is the role of ketone bodies?
What is the role of ketone bodies?
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Why is fatty acid oxidation the main source of acetyl-CoA for ketogenesis?
Why is fatty acid oxidation the main source of acetyl-CoA for ketogenesis?
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What enzymes are important in ketogenesis?
What enzymes are important in ketogenesis?
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When is ketogenesis important?
When is ketogenesis important?
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β-oxidation
β-oxidation
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Refsum's Disease
Refsum's Disease
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De Novo Fatty Acid Synthesis
De Novo Fatty Acid Synthesis
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HMG-CoA reductase
HMG-CoA reductase
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How does Acetyl-CoA get from the mitochondria to the cytosol?
How does Acetyl-CoA get from the mitochondria to the cytosol?
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What is Acetyl-CoA Carboxylase (ACC)?
What is Acetyl-CoA Carboxylase (ACC)?
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What is Fatty Acid Synthase (FAS)?
What is Fatty Acid Synthase (FAS)?
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Where does the NADPH for fatty acid synthesis come from?
Where does the NADPH for fatty acid synthesis come from?
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How does malonyl-CoA control fatty acid metabolism?
How does malonyl-CoA control fatty acid metabolism?
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Study Notes
Regulation of Cholesterol Synthesis
- Key enzyme: HMG-CoA reductase is the rate-limiting reaction
- Enzyme activity is controlled by reversible phosphorylation/dephosphorylation.
- The active form (a) is dephosphorylated
- Phosphorylation is catalyzed by AMP-activated protein kinase (AMPK).
1. Hormonal Regulation
-
Feeding and insulin
- Insulin stimulates cholesterol synthesis
- Insulin acts as an inducer for HMG-CoA reductase gene
- Activates protein phosphatase which catalyze dephosphorylation of HMGCoA reductase
-
Fasting and glucagon
- Glucagon acts as a repressor for HMGCoA reductase.
2. Allosteric Regulation
- Cholesterol is a group of drugs that act through competitive inhibition of HMG-CoA reductase (structural analogs to HMG-CoA) and help to lower plasma cholesterol.
- Statins are a group of drugs that act through competitive inhibition of HMG-CoA reductase (structural analogs to HMG-CoA) and help to lower plasma cholesterol
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