University:
Liberty University
Course:
BIOM 500 | Introduction to Biomedical Sciences
Academic year:

2024
Views:

271

Pages:

9
Author:

Sheha A.

Fate of Fatty Acids 1. Fatty acids can be oxidized to Acetyl-CoA Acetyl-CoA is a key metabolic intermediate. Via beta-oxidation, fatty acids are broken down into acetyl-CoA units. 2. Acetyl-CoA can be used for energy production In the citric acid cycle (Krebs cycle), acetyl-CoA is oxidized to produce energy in the form of ATP. 3. In times of plenty, acetyl-CoA can be converted to ketone bodies or fatty acids. Ketone bodies are an alternative energy source for the brain and other tissues when glucose is not available. Fatty acids can be stored as triglycerides in adipose tissue. Oxidation of Fatty Acids The fatty acid is activated to form fatty acyl-CoA. Beta-oxidation occurs in the mitochondria. A two-carbon unit (acetyl-CoA) is cleaved off in each cycle of beta-oxidation. This process continues until the entire fatty acid is broken down into acetyl-CoA molecules. Acetyl-CoA Acetyl-CoA can enter the citric acid cycle to produce ATP. It can also be used to synthesize fatty acids or ketone bodies. Beta-Oxidation of Fatty Acids Involves three steps: Oxidation Hydration Thiolysis Regulation of Fatty Acid Oxidation The rate of fatty acid oxidation is regulated by hormones, such as insulin and glucagon. Insulin inhibits fatty acid oxidation, while glucagon stimulates it. Oxidation of Fatty Acids Beta-oxidation Activation of Fatty Acids: Fatty acids are activated to form fatty acyl-CoA. This involves the addition of CoA-SH to the carboxyl group of the fatty acid. Transport into Mitochondria: Fatty acyl-CoA is transported into the mitochondria. Beta-Oxidation Cycle: A series of reactions that cleave two-carbon units (acetyl-CoA) from the fatty acyl-CoA chain. Involves oxidation, hydration, oxidation, and thiolysis steps. Acetyl-CoA Acetyl-CoA can enter the citric acid cycle for further oxidation and energy production. It can also be used for fatty acid synthesis or ketone body formation. Key Enzymes: Acyl-CoA synthetase: Catalyzes the activation of fatty acids. Carnitine acyltransferase: Transports fatty acyl-CoA into the mitochondria. β-oxidation enzymes: Catalyze the oxidation, hydration, oxidation, and thiolysis steps. Energy Yield Each cycle of beta-oxidation produces 1 FADH2, 1 NADH, and 1 acetyl-CoA. These molecules enter the electron transport chain to generate ATP. Overall, beta-oxidation is a crucial process for energy production from fatty acids. Irreversible Reactions Irreversible reactions occur in one direction only. They are often coupled to exergonic reactions to release energy. These reactions are important for driving metabolic processes. Four Steps: Initial Step of Fatty Acid Oxidation: Fatty acids are activated by CoA-SH to form fatty acyl-CoA. This is an irreversible step, committed to oxidation. Fatty Acid Oxidation: Fatty acids are oxidized through a series of reactions, including dehydrogenation, hydration, and oxidation. Each cycle of beta-oxidation produces acetyl-CoA, FADH2, and NADH. This step is irreversible. Citric Acid Cycle: Acetyl-CoA enters the citric acid cycle, where it is further oxidized to produce CO2 and reduced electron carriers (NADH and FADH2). This is an irreversible process. Electron Transport Chain: Electrons from NADH and FADH2 are transferred to the electron transport chain. This process is coupled to the synthesis of ATP. The final electron acceptor is oxygen, which is reduced to water. This step is essentially irreversible.