Mitochondrial fatty acid oxidation

Definition

Mitochondrial fatty acid oxidation is the metabolic process by which fatty acids are broken down in the mitochondria to produce energy in the form of ATP. This process involves several key steps, including the activation of fatty acids, their transport into the mitochondria, and their subsequent degradation through beta-oxidation, which generates acetyl-CoA and reducing equivalents for the electron transport chain.

5 Must Know Facts For Your Next Test

1. Mitochondrial fatty acid oxidation is primarily responsible for providing energy during periods of fasting or prolonged exercise when carbohydrate stores are low.
2. The process starts with the activation of fatty acids to form fatty acyl-CoA, which is then transported into the mitochondria via the carnitine shuttle.
3. Once inside the mitochondria, fatty acids undergo a cycle of beta-oxidation, where they are broken down into two-carbon units of acetyl-CoA.
4. The generated acetyl-CoA can enter the Krebs cycle to produce ATP, while NADH and FADH2 produced during oxidation feed into the electron transport chain to generate additional ATP.
5. Defects in mitochondrial fatty acid oxidation can lead to metabolic disorders and energy deficiencies, highlighting its importance in cellular metabolism.

Review Questions

• How does mitochondrial fatty acid oxidation contribute to energy production during fasting or prolonged exercise?
  • During fasting or prolonged exercise, glucose availability is reduced, leading the body to rely more on fat stores for energy. Mitochondrial fatty acid oxidation breaks down stored fatty acids to produce acetyl-CoA, which enters the Krebs cycle, generating ATP. This process provides a crucial source of energy when carbohydrates are scarce, allowing for continued physical activity and maintaining cellular functions.
• Discuss the role of the carnitine shuttle in mitochondrial fatty acid oxidation and why it is necessary for this process.
  • The carnitine shuttle is essential for transporting long-chain fatty acids from the cytosol into the mitochondria because these fatty acids cannot freely cross the mitochondrial membrane. In this shuttle system, fatty acyl-CoA is converted to fatty acylcarnitine, which can be transported across the membrane. Once inside the mitochondria, carnitine is removed, allowing fatty acyl-CoA to undergo beta-oxidation. Without this shuttle, mitochondrial fatty acid oxidation would be severely limited.
• Evaluate how defects in mitochondrial fatty acid oxidation can impact overall metabolic health and lead to specific disorders.
  • Defects in mitochondrial fatty acid oxidation can disrupt normal energy production and lead to a range of metabolic disorders. For example, a deficiency in enzymes involved in beta-oxidation can result in an inability to properly break down fats, leading to muscle weakness, hypoglycemia, and accumulation of toxic intermediates. These disorders often manifest during periods of increased energy demand, such as fasting or exercise, emphasizing the critical role of this metabolic pathway in maintaining energy homeostasis and overall metabolic health.

Related terms

Beta-Oxidation: A series of enzymatic reactions that degrade fatty acids into acetyl-CoA units, releasing energy in the form of NADH and FADH2.

Carnitine Shuttle: A transport system that facilitates the movement of long-chain fatty acids from the cytosol into the mitochondria for beta-oxidation.

Acetyl-CoA: A key metabolic intermediate produced during fatty acid oxidation that enters the Krebs cycle for further energy production.