Krebs cycle or TCA cycle occurs in the mitochondrial matrix, a dense solution in the innermost part of the mitochondria. Pyruvate, which is formed in the cell cytosol, is imported into the mitochondria, where it is converted to acetyl CoA. The acetyl CoA is transferred to the matrix of the mitochondria, which contains all the enzymes and coenzymes required for the biochemical reactions of the Krebs cycle.