The transition reactions take place in the matrix of the mitochondrion. The process will always continue to take place
as long as there is a sufficient amount of oxygen in the mitochondrion.
Pyruvate enters the matrix by a protein located on the external membrane. NAD takes two electrons that oxidizes
pyruvate and releases carbon dioxide. The two carbon molecule, acetyl bonds with a coenzyme called coenzyme A and forms acetyl
Acetyl CO-A is what begins the Kreb's cycle. Sugars provide the acetyl to produce ATP.
Directly after gylcolysis, if acetyl CO-A is not formed cellular respiration will stop. Meaning the organism will die.