Citric acid cycle
The citric acid cycle, also known as the Krebs cycle or tricarboxylic acid cycle, is a series of chemical reactions that occur in all aerobic organisms to generate energy. It is named after its discoverer, Sir Hans Krebs, who outlined the pathway in 1937.
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It is named after its discoverer, Sir Hans Krebs, who outlined the pathway in 1937. This cycle takes place in the mitochondria of eukaryotic cells and the cytoplasm of prokaryotic cells. The citric acid cycle plays a crucial role in the cellular respiration process, where it oxidizes acetyl-CoA, a molecule derived from carbohydrates, fats, and proteins. The carbon atoms from acetyl-CoA are gradually released in a series of reactions, ultimately converting them to carbon dioxide. This process also generates high-energy molecules such as NADH and FADH2, which are utilized in the electron transport chain to produce adenosine triphosphate (ATP), the energy currency of cells. The citric acid cycle consists of eight enzymatic reactions, with each step catalyzed by a specific enzyme. These reactions involve the rearrangement of carbon atoms and the transfer of electrons and protons. The cycle begins with the condensation of acetyl-CoA with oxaloacetate to form citrate, which undergoes numerous chemical transformations to produce oxaloacetate again, completing the cycle. Apart from its role in energy production, the citric acid cycle also serves as a hub for other metabolic pathways. It provides precursors for the synthesis of amino acids, lipids, and other biomolecules essential for cellular functions. Furthermore, several intermediates of the cycle are utilized as signaling molecules, connecting the citric acid cycle to various cellular processes. Disruptions in the citric acid cycle can have severe consequences for cellular metabolism. Dysfunctional enzymes or deficiencies in cofactors can lead to metabolic disorders, such as fumarase deficiency or succinate dehydrogenase deficiency. These disorders can cause a range of symptoms, including developmental delays, intellectual disabilities, and neurological problems. Overall, the citric acid cycle is a fundamental metabolic pathway that plays a crucial role in energy production and the synthesis of biomolecules in all living organisms. Its intricate series of reactions and its integration with other metabolic pathways make it a key determinant of cellular health and function.