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Which stages of cellular respiration occur in or involve mitochondria?
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mitochondrion
Mitochondria (red) are found throughout the cytoplasm of almost all eukaryotic cells (cell nucleus is shown in blue; cytoskeleton is shown in yellow).
In eukaryotic cells, the mitochondrion serves as the primary site for the later stages of cellular respiration, where the majority of adenosine triphosphate (ATP) is produced.1
While the initial stage, glycolysis, occurs in the cytoplasm, the subsequent stages take place within the mitochondria:
- Pyruvate Oxidation: Following glycolysis, pyruvate molecules enter the mitochondria, where they are converted into acetyl coenzyme A.1
- Tricarboxylic Acid (TCA) Cycle: Also known as the Krebs or citric acid cycle, this series of reactions occurs in the mitochondrial matrix. It processes acetyl coenzyme A to produce carbon dioxide and high-energy electron carriers, specifically NADH and FADH2.12
- Oxidative Phosphorylation: This final stage occurs within the cristae (the inner mitochondrial membrane). The electron transport chain utilizes the electrons from NADH and FADH2 to create an electrochemical gradient, which powers the synthesis of ATP through the action of the F1F0-ATPase complex.13