Although we study the citric acid cycle as the final stage oxidation of carbon from glucose, an in-depth look at the cycle shows intermediates entering and leaving the cycle from a number of metabolic pathways. with all of these demands on the cycle, how does it maintain a minimal level of oxaloacetate (oaa) to allow the cycle to function? a-oaa can be formed by the condensation of two moles of acetyl coa and occurs when the energy charge of the cell is high. b-the rate of the cycle is increased when the cell has high levels of nadh. c-isocitrate dehydrogenase is allosterically inhibited by adp, which signifies the need for more energy. d-oaa is formed directly via the deamination of glutamate. e-oaa is synthesized via pyruvate carboxylase in an anapleurotic reaction that occurs when acetyl coa is present, such as from fatty acid breakdown