Eventually citric acid is made into a 4-carbon molecule and the cycle starts over. The Krebs cycle produces two ATP molecules.
Last is the electron transport chain in the inner membrane of mitochondria. It uses high-energy electrons to turn ADP back into ATP. NADH and FADH2 move high-energy electrons through one side of the electron transport chain to the other by carrier proteins, where an enzyme joins electrons with hydrogen ions producing water. While these electrons are carried through the electron transport chain, their energy moves hydrogen ions across the membrane. The place which the H+ ions used to be is now negatively charged. As the H+ ions move they go through ATP synthase. Everytime they go through the ATP synthase, it spins and attaches a phosphate to low-energy ADP resulting in ATP. The electron transport chain ends in the total of 34 ATP molecules.
During cellular respiration the cell can make 36 ATP molecules per glucose. If no oxygen is available then the cell is forced into fermentation after glycolysis. Fermentation releases the energy of food molecules without oxygen making it anaerobic. However cellular respiration produces a lot more ATP molecules then fermentation. The three events of cellular respiration are glycolysis, the Krebs cycle and the electron transport chain.
Cellular respiration is the process in which energy is released by breaking down food with the help of oxygen. The equation for it is, oxygen plus glucose turn into carbon dioxide plus water plus energy. Cellular respiration has three main events, glycolysis, the Krebs cycle and the electron transport chain, and each produce ATP.
Glycolysis is the first part of the cellular respiration where one glucose molecule is split in half making two pyruvic acid molecules. Glycolysis takes place in the cytoplasm, and is started by two ATP molecules with a result of four. It moves four high energy electrons and gives them to the electron carrier NAD+ making it NADH. Glycolysis happens very fast and does not need oxygen.
After glycolysis, pyruvic acid is passed to the Krebs cycle, also known as the citric acid cycle, in the mitochondria. Upon entering the Krebs cycle one of the pyruvic acids’ carbon atoms are taken and made into a carbon dioxide molecule, which is eventually released. A compound called coenzyme A joins two of the 3-carbon atoms forming acetyl-CoA. Acetyl-CoA combines a 4-carbon compound with a 2-carbon acetyl group making citric acid. Throughout the process more carbon is harvested out and released as carbon dioxide, and while the carbon is taken out electrons add to NAD+ and FAD to make NADH and FADH2.