The Krebs Cycle

The Krebs Cycle (also known as the citric acid cycle, TCA cycle, or the tricarboxylic acid cycle) is the central part of the catabolic pathway, a cyclic biochemical aerobic process. During this cycle, the conversion of two- and three-carbon compounds, which are intermediate products in the breakdown of carbohydrates, fats, and proteins in living organisms, leads to the production of CO2. Simultaneously, the released hydrogen is directed into the tissue respiration chain, where it is further oxidized to water, directly participating in the synthesis of ATP (12 molecules for each cycle of acetyl-CoA oxidation).

The Krebs Cycle is a crucial stage in the respiration of all oxygen-utilizing cells, serving as a central hub connecting multiple metabolic pathways within the organism. Besides its significant role in energy production, this cycle also plays a substantial role in the generation of precursor molecules. These precursors are subsequently utilized in other biochemical processes to synthesize amino acids, carbohydrates, fatty acids, and more. The Krebs Cycle takes place inside the mitochondria, specifically on the cristae. The enzymes involved in the Krebs Cycle, except for one, are located in the free state within the mitochondrial matrix. The exception is succinate dehydrogenase, which participates in succinic acid oxidation and is embedded in the inner mitochondrial membrane, incorporating into its lipid bilayer. Hormones that promote aerobic glucose breakdown, such as adrenaline and insulin, accelerate the progression of reactions in the Krebs Cycle.