KREBS CYCLE

Abstract

The Krebs cycle, also known as the citric acid cycle or tricarboxylic acid (TCA) cycle, is a fundamental metabolic pathway in aerobic organisms that takes place in the mitochondria. It is a key process in cellular respiration, converting carbohydrates, fats, and proteins into energy in the form of adenosine triphosphate (ATP). The cycle begins with the combination of acetyl-CoA and oxaloacetate to form citrate, followed by a series of enzyme-catalyzed reactions that release carbon dioxide, generate reducing equivalents (NADH and FADH2), and produce ATP through substrate-level phosphorylation. These reducing equivalents then transfer electrons to the electron transport chain, leading to the synthesis of the majority of cellular ATP. In addition to energy production, the Krebs cycle plays a central role in biosynthesis. Its intermediates serve as precursors for amino acids, nucleotide bases, fatty acids, and heme groups, linking energy metabolism with the synthesis of essential biomolecules. The cycle is regulated by allosteric enzymes and feedback mechanisms to maintain cellular energy balance and respond to changes in nutrient availability. Dysregulation or defects in the Krebs cycle are associated with metabolic disorders, neurodegenerative diseases, and cancer, underscoring its importance in health and disease. Studying the Krebs cycle provides insight into cellular energy metabolism, mitochondrial function, and biochemical regulation. It is essential for understanding how cells generate energy efficiently, adapt to environmental changes, and integrate metabolic signals to sustain life. Knowledge of this cycle is critical for students, researchers, and healthcare professionals in biochemistry, medicine, pharmacology, and related fields.