Now, unlike NADH, our fadh two only Synthesizes two ATP per a single fadh two. And the reason for that is because our Fadh two begins on protein complex two but the NADH begins on protein complex number one to the left. And NADH basically pumps four more protons than Fadh two because NADH begins earlier, before Fadh two. So for a single Fadh two that is synthesized during the citric acid cycle when we actually utilize and oxidize the Fadh two and two Fad we produce only two ATP molecules. But for the case of NADH that is formed within the mitochondrial matrix we form three ATPs per one NADH. So we conclude that NAD plus and Fad plus molecules are cofactor molecules that assist the enzymes involved in cellular respiration.