The main function of the Krebs cycle is energy production, according to the Research Collaboratory for Structural Bioinformatics Protein Data Bank. The Krebs cycle, also known as the tricarboxylic acid cycle or the citric acid cycle, is at the center of cellular metabolism.
There are eight reactions in the Krebs cycle. The cycle starts with the addition of an acetyl group to oxaloacetate. After the eight reactions, the acetyl group is broken apart, and oxaloacetate is restored, thereby completing the cycle.
The Krebs cycle finishes the breakdown of sugar started by glycolysis and produces adenosine triphosphate, called ATP. ATP is the molecular currency of the cell and stores and transports energy within it. The Krebs cycle is at the center of biosynthetic reactions and provides intermediates that are used to make amino acids and other molecules.
The Krebs cycle also provides electrons for the process of oxidative phosphorylation. Oxidative phosphorylation is a major source of ATP and energy. The electrons are stored in the carrier molecule NADH. The electrons drive a proton gradient that powers ATP synthase. ATP synthase is the enzyme that makes ATP. The Krebs cycle takes place in the mitochondria, and the proton gradient is generated in the mitochondrial membrane.