Citric Acid Cycle Step by Step: A Complete Breakdown of Cellular Respiration’s Energy Powerhouse
The citric acid cycle, also known as the Krebs cycle or tricarboxylic acid (TCA) cycle, is a series of chemical reactions used by all aerobic organisms to generate energy. This pathway occurs in the mitochondrial matrix and serves as a central metabolic hub, linking carbohydrate, fat, and protein metabolism. On top of that, understanding the citric acid cycle step by step reveals how cells convert acetyl-CoA into usable energy, carbon dioxide, and high-energy electron carriers. In this article, we will explore the citric acid cycle step by step, breaking down each reaction, intermediate, and energy yield with clarity and precision.
The citric acid cycle step by step begins with the condensation of acetyl-CoA and oxaloacetate. In practice, acetyl-CoA, derived from the breakdown of pyruvate, fatty acids, or amino acids, combines with the four-carbon molecule oxaloacetate to form citrate, a six-carbon compound. This reaction is catalyzed by the enzyme citrate synthase and releases coenzyme A, which can be reused in other metabolic pathways. The formation of citrate marks the official start of the citric acid cycle step by step, committing the carbon skeleton to a sequence of transformations that will ultimately regenerate oxaloacetate and continue the cycle Practical, not theoretical..
Following citrate formation, the citric acid cycle step by step continues with the isomerization of citrate to isocitrate. Plus, this transformation is not a simple rearrangement; it involves the removal of a water molecule to form cis-aconitate, followed by the addition of water in a different position to yield isocitrate. Practically speaking, the enzyme aconitase facilitates this step, positioning the molecule for the subsequent oxidative reactions. Isocitrate is now ready for the first oxidation reaction of the citric acid cycle step by step, which will produce the first NADH of the cycle.
Step 3 of the citric acid cycle step by step involves the oxidative decarboxylation of isocitrate to alpha-ketoglutarate. Isocitrate dehydrogenase catalyzes this reaction, removing a carbon dioxide molecule and transferring hydride ions to NAD⁺, forming NADH. This step is a key regulatory point in the cycle, as isocitrate dehydrogenase is allosterically activated by
