A metabolic pathway "loop" in which acetyl CoA from the transition reaction is added to a 4-carbon intermediate (oxaloacetate) to produce 6-carbon citric acid, during which important electron carriers are reduced. In addition to being an important component of glucose metabolism, several intermediates of the cycle form important molecules, making the process both catabolic and anabolic. Occurs in the mitochondrial matrix for eukaryotes and in the cytoplasm for prokaryotes

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