What is the Krebs cycle?

The Krebs cycle is one of the steps of cellular respiration - the process that allows organic molecules to be broken down in a series of stages to release chemical potential energy, which is used to synthesize ATP. After glycolysis where glucose is broken down to pyruvate and some ATP is created, and the link reaction where pyruvate is decarboxylated (this means that carbon dioxideis removed), dehydrogenated (hydrogen is removed )and combined with coenzyme A (CoA) to give acetyl coenzyme A, the molecule enters the Krebs cycle (also known as the citric acid cycle or tricarboxylic acid cycle). This is a closed pathway of enzyme controlled reactions. Acetyl coenzyme A combines with a four-carbon compound (oxaloacetate) to form a six-carbon compound (citrate). The citrate is decarboxylated and dehydrogenated in a series of steps, to yield carbon dioxide, which is given off as a waste gas, and hydrogens which are accepted by the carriers NAD and FAD. Oxaloacetate is regenerated to combine with another acetyl coenzyme A. For each turn of the cycle, two carbon dioxide molecules are produced, one FAD and three NAD molecules are reduced, and one ATP molecule is generated via an intermediate compound.Although part of aerobic respiration no oxygen is used for this reaction; however it will later be required in oxidative phosphorylation. It is important to note that while the cycle produces some ATP, its most important contribution to respiration is the release of hydrogens for oxidative phosphorylation.