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Biomedical Basics

Citric acid cycle (Krebs cycle)

  • Created by Henry Stewart Talks
Published on October 30, 2025   5 min

A selection of talks on Biochemistry

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Welcome to this lecture on Citric Acid Cycle (Krebs Cycle), providing an overview of the central role of the citric acid cycle in aerobic metabolism, tracing how acetyl-CoA enters after glycolysis and fuels the cycle's reactions. We will discuss the pathway's steps, its production of high-energy electron carriers (NADH and FADH₂), and its function in both energy generation and biosynthesis. Additionally, we will explore mechanisms that regulate the cycle in response to cellular energy needs, and highlight how cycle intermediates are replenished to sustain overall metabolic balance.. The citric acid cycle, also known as the Krebs cycle or tricarboxylic acid cycle, is central to aerobic metabolism. Acetyl-CoA enters after glycolysis, when pyruvate is transported into the mitochondrial matrix and converted to acetyl-CoA by the pyruvate dehydrogenase complex, producing NADH and carbon dioxide. The two-carbon acetyl group reacts with four-carbon oxaloacetate to form six-carbon citrate, leading to transformations that regenerate oxaloacetate and keep the cycle going. The cycle is named for its process of combining the acetyl group with a regenerated molecule, thus ensuring continuous fuel processing. In the citric acid cycle, the main goal is the complete oxidation of the acetyl group from acetyl-CoA. As the cycle proceeds, citrate is isomerized to isocitrate, then converted by isocitrate dehydrogenase

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