Essential fatty acids are primarily converted to two-carbon acetyl CoA molecules through a process called fatty acid oxidation (beta-oxidation). These acetyl CoA molecules then enter the Krebs cycle (also known as the citric acid cycle or tricarboxylic acid cycle) to generate ATP, the cell's primary energy currency.
The Process Explained
Fatty acid oxidation, specifically beta-oxidation, is a catabolic process where fatty acids are broken down. Here's a simplified breakdown:
- Activation: Fatty acids are activated by attaching Coenzyme A (CoA). This requires ATP.
- Transport: The activated fatty acid is transported into the mitochondria (the cell's power plant) for oxidation.
- Beta-Oxidation: In the mitochondria, the fatty acid undergoes a series of reactions that cleave off two-carbon units in the form of acetyl CoA. Each cycle also produces FADH2 and NADH.
- Krebs Cycle (Citric Acid Cycle): Acetyl CoA enters the Krebs cycle, where it is further oxidized, producing more ATP, NADH, FADH2, and carbon dioxide.
- Electron Transport Chain: NADH and FADH2 produced in beta-oxidation and the Krebs cycle donate electrons to the electron transport chain, driving ATP synthesis through oxidative phosphorylation.
Ketone Body Formation
If the amount of acetyl CoA produced through fatty acid oxidation exceeds the capacity of the Krebs cycle (often occurring during starvation, uncontrolled diabetes, or a very low-carbohydrate diet), the excess acetyl CoA is diverted to a process called ketogenesis. This process results in the formation of ketone bodies, such as acetoacetate, beta-hydroxybutyrate, and acetone. Ketone bodies can then be used as an alternative fuel source by the brain and other tissues.
Summary
In summary, essential fatty acids are primarily broken down into acetyl CoA for energy production via the Krebs cycle. Excess acetyl CoA can then be converted into ketone bodies.
