2nd phase of cellular respiration--called TCA cycle or Krebs' cycle.
Actually, Glucose is split into two molecules of Pyruvic acid in cytoplasm during first phase of respiration ---called Glycolysis. The pyruvic acid then enters Mitochondriawhere pyruvate oxidation takes place resulting in the formation of Acetyl-coA. This compound is stepwise broken down in the matrix of mitochondria releasing all the energy,i.e 36ATP. It is way mitochondria is called energy house of a cell.
Mitochondrial matrix is the site of the citric acid cycle, a part of cellular respiration. It is also the site of electron transport chain
  * 3 years ago

Inner Mitochondria & Matrix
Inside the deepest compartments of the mitochondria is the mitochondrian matrix. It is in the matrix that cellular respiration occurs, where pyruvate (a product of glycolysis in the cytosol) is converted to Carbon Dioxide and water. The matrix is the site of the the citric acid cycle, whereby the electron transport chain is used to setup a proton gradient between the inner and outer membrane of the mitochondria, known as the inter membrane space. The protons in the inter membrane space accumulate to a point that the concentration gradient causes the protons to flow back into the matrix.
It is the inner membrane that is studded with the proteins necessary for the electron transport chain, such as the cytochrome electron shuttles. Upon reentering the matrix, the H+ go through ATP synthase, which in turns powers the synthase to phosphorylate adenosine diphosphate (ADP) to adenosine triphosphate (ATP). The ATP can be used later on to be coupled with thermodynamically unfavorable reactions to allow those chemical reactions to proceed. The inner membrane is folded and convoluted which allows for a greater surface area to utulize for the electron transport chain. These convolutions are what make up the cristae.
Interestingly enough the matrix of the...