Now, a single glucose is broken down into two Pyruvate molecules in glycolysis. And in the process, we also generate two ATP molecules and we produce two NADH molecules. Now, the ATP molecules can be used directly by the cell to power some type of biological process in that cell. But to produce ATP molecules from NADH, the NADH must move onto the electron transfer chain found on the inner membrane of the mitochondrion. So we have the outer membrane, the inner membrane, we have electron transport chain, and this is the matrix of the mitochondria and this is the intermembrane space. Now the question is how many ATP molecules do we actually form when a single NADH is transported onto the electron transport chain from the cytoplasm?