 in the cellular respiration after glycolysis, the next step is citric acid cycle or crab cycle. Where is that happening? Inside of the matrix of mitochondria. Remember, glycolysis is happening outside of mitochondria in the cytoplasm. Then through the process of decarboxylation, we have acetylcoenzyme A entering the cycle for each pyruvate. So one molecule of glucose has two cycles of the citric acid cycle or crab cycle. I need you to remember that for each of the steps that are shown here, each step is controlled by the separate enzyme. So citric acid is the first one in this cycle. And through the series of steps, we have release of the NADH and H molecules. NADH is a debit card that is going to be utilized in the process of the oxidative phosphorylation of the electron transport chain. So that's potential. That is a dish that is bringing that energy to the place where it can be harvested and transformed into what we can utilize. One carbon dioxide is lost in the process here between formation of the citric acid and alpha-cataglutarate. The other carbon dioxide is used. Only one ATP molecule is produced from the ADP, adding phosphate group. And we have another enzyme here, which is FADH2 that will also bring that potential to the oxidative phosphorylation and where we can harvest the energy. Overall, CREB cycle is happening for each of the two carbon atoms that are attached to the settle coins I made. It doesn't need to be sugar. Like for instance, fatty acids. Some of them can have 18 or 20 or whichever number of the carbons in them. And every time two are entering the CREB cycle. So that's why the lipids are, especially FADHs, they're actually energy storage. Because there's a tremendous amount of energy that is captured in one molecule. So from glucose, we have two CREB cycle entries through the two pyruvates entering as a settle coenzyme A into the cycle. And we can harvest so much energy. For one molecule of the fatty acids, every time two carbons are entering the process. And you can imagine how much of the high energy is harvested there, how much of the ATPs is harvested. The last, but probably the most important part of the solar respiration is the electron transport chain or the oxidative phosphorylation. All the energy that is released is actually utilizing protons. Here in the inner membrane of the mitochondria, there is a series. There is a cascade of the enzymes that are just bringing to each other molecules that eventually are leading to the high concentration of the H plus or the proton ions outside in between the two membranes. So that eventually it is pretty much like when you have a river dam, there is a huge potential energy, huge power that is on one side of the membrane and the lack of the proton ions on the other side. So that potential is utilized by the proton pump. Proton pump is where ATP, where that energy that is entered through NADH and FADH2, when that is cached into ATP. So 34 ATPs are actually made per one glucose molecule right here and the oxygen is the final acceptor of the potential of the electrons. So one of the major factors here in the electron transport chain is something that you may have heard of, which is called coenzyme Q10 or CoQ10, as you can find. If we don't have that particular molecule, the transport chain is not happening. And the other name for the coenzyme 10 is ubiquinone, which means it's present everywhere. What that means is that it needs energy in order to utilize it. You can think about all the glucose that you can take if you don't have that particular coenzyme Q, which our body can actually make in most of the cases, that can be a trouble. We cannot utilize that energy, which gives the idea about why vitamins are so important because coenzyme Q is vitamin. It is part of the enzyme that is needed in this process. Organs that are working constantly, like our heart, are the ones who are needing energy in the highest amount. And that explains why, for instance, coenzyme Q10 is so-called heart medicine, especially for the people who have weakened heart. Some of the medication that we are taking or some of the environmental pollutants can interfere with the electron transport chain. Some of the major poisons are the ones who are actually acting as blockers in this electron transport chain. That's why they're so dangerous, like cyanide, for instance. It is binding in the electron transport chain place. So how many ATPs are overall released? From one, glucose molecule. We have first investment phase. So four ATPs are released during the glycolysis. So we harvested four ATP, but we gave away two ATPs. And through NADH, when the 3C pyruvate converted into acetyl-coenzyme Q and dichroboxylation happened, that's NADH formation. And inside of the CRAM cycle, we have one ATP per pyruvate, but we also have plenty of NADH and FADH2, which overall leads to 36 ATP molecules, which are built from glucose, one glucose molecule. Again, the number really depends whether it's glucose entering or whether we have fatty acids and so forth. And if you remember from CRAM cycle, this number of the ATP molecules can be huge depending on what was the original input in the cell respiration. We'll talk more about what happens when the oxygen is not present in the next session.