Podcast
Questions and Answers
What metabolic state favors fatty acid synthesis and how does it affect the Krebs Cycle?
What metabolic state favors fatty acid synthesis and how does it affect the Krebs Cycle?
High ATP levels favor fatty acid synthesis, inhibiting the Krebs Cycle and causing a build-up of acetyl CoA.
Explain the role of the citrate shuttle in fatty acid metabolism.
Explain the role of the citrate shuttle in fatty acid metabolism.
The citrate shuttle transports acetyl CoA from the mitochondria to the cytosol by converting it into citrate, which can cross the membrane.
Describe the purpose of the carnitine shuttle in fatty acid metabolism.
Describe the purpose of the carnitine shuttle in fatty acid metabolism.
The carnitine shuttle facilitates the transport of long acyl CoA chains across the mitochondrial membrane by converting them into acyl carnitine.
What are the key products generated from one round of beta oxidation?
What are the key products generated from one round of beta oxidation?
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What triggers the increased production of ketone bodies in the body?
What triggers the increased production of ketone bodies in the body?
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How do ketone bodies evade reliance on carbohydrates for energy?
How do ketone bodies evade reliance on carbohydrates for energy?
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What can lead to diabetic ketoacidosis and what are its key physiological effects?
What can lead to diabetic ketoacidosis and what are its key physiological effects?
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What are the two main enzymes involved in the synthesis of β-hydroxybutyrate from acetoacetate?
What are the two main enzymes involved in the synthesis of β-hydroxybutyrate from acetoacetate?
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Describe the relationship between acyl CoA and the Krebs Cycle during fatty acid metabolism.
Describe the relationship between acyl CoA and the Krebs Cycle during fatty acid metabolism.
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What are the two pathways that acetoacetate can undergo after its formation?
What are the two pathways that acetoacetate can undergo after its formation?
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Study Notes
Fatty Acid Metabolism
- Fatty acid metabolism occurs when the body needs energy and blood glucose is low.
- Fatty acids are long acyl CoA chains.
- Dietary fatty acids typically have more than 14 carbons.
- Fatty acids longer than 12 carbons cannot diffuse through the mitochondrial membrane. Therefore, they must be transported.
Carnitine Shuttle
- Acyl CoA is converted to acyl carnitine to cross the mitochondrial membrane. This process is catalyzed by carnitine acyltransferase 1 (CAT1).
- Acyl carnitine is reformed to acyl CoA on the inner mitochondrial membrane side by carnitine acyltransferase 2 (CAT2).
- Carnitine shuttles the acyl CoA across the membrane.
Beta Oxidation
- Once acyl CoA crosses the membrane, it can be oxidized.
- This process involves sequentially removing 2-carbon units through oxidation.
- Each round of beta oxidation produces 1 NADH, 1 FADH2, and 1 acetyl CoA.
- FADH2 and NADH enter the oxidative phosphorylation pathway.
- Acetyl CoA enters the Krebs cycle.
Ketones
- Ketone production often occurs slowly during normal feeding.
- In response to carbohydrate shortages, ketone body production increases.
- This is due to increased beta oxidation and acetyl CoA production exceeding the Krebs cycle's capacity.
- Ketone bodies (such as acetone, acetoacetate) are used instead of carbohydrates to preserve glucose.
- Ketones are primarily used by cardiac and skeletal muscle.
- Diabetic ketoacidosis results from excessive ketone production, typically in untreated diabetes mellitus. Excessive ketone production impairs O2 binding to hemoglobin (hence hyperventilation). Low pH, PCO2, and HCO3-, and high PO2 typically occur.
- Ketones are strong acids.
Citrate Shuttle
- Acetyl CoA cannot directly enter the mitochondria.
- It combines with oxaloacetate to form citrate.
- Citrate crosses the mitochondrial membrane.
- Citrate is then converted back to oxaloacetate and acetyl CoA inside the mitochondria.
- Oxaloacetate is recycled back into the Krebs cycle.
- Acetyl CoA is used for energy production or fatty acid synthesis.
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Description
This quiz covers the essential processes of fatty acid metabolism, including the carnitine shuttle and beta oxidation. It highlights the significance of acyl CoA and its transformation for energy production in cells. Test your knowledge on the details and mechanisms involved in these metabolic pathways.
