1. AP Biology Cellular Respiration – Glycolysis, Krebs Cycle, and ETC Part 2

2. ATP Structure Quick Review – How is ATP used as an energy molecule in living organisms? What is it about the molecule that allows it to hold free energy?

3. Phosphorylation using Free energy

4. Glycolysis Overview – Big Picture Glycolysis is a cytoplasmic process where one molecule of Glucose (or another carbon-based molecule) is ultimately broken down into two pyruvates. This happens with or without Oxygen. These pyruvates will then enter the mitochondria and the Krebs Cycle. A net of 2 ATP are produced and 2 NADH are also produced.

5. Energy Investment Phase & Phosphofructokinase We will follow the carbons and pay special attention to the use of 2 ATP. Why do this?

6. Energy Investment Phase This part of Glycolysis is called the Energy Investment Phase, because it costs the cell 2 ATP to phosphorylate the glucose molecule. The end product of this part of glycolysis is two molecules of G3P. See the connection to photosynthesis?

7. Energy Payoff Phase We will follow the carbons again and pay close attention to production of 2 NADH and 4 ATP.

8. Energy Payoff Phase In this part of glycolysis, the cell produces 4 ATP molecules by removing phosphates from the carbon-based molecules already produced in the process. It also creates 2 NADH. This gives the whole process a net of 2 ATP made. The ultimate end product is 2 Pyruvates, which will be slightly modified and added to the Krebs Cycle

9. Is Oxygen present?

10. Cellular Respiration Pyruvate Conversion and Krebs Cycle

11. Pyruvate Conversion The Krebs cycle is not perfect, so pyruvate must be further converted before it can enter the cycle. To do this, 1 carbon dioxide is removed from pyruvate and a coenzyme (Coenzyme A) is added to the remaining molecule. This molecule, Acetyl Coenzyme A, can now enter the Krebs cycle. Also, one NADH and one CO 2 are produced.

12. Pyruvate Conversion CYTOSOL Pyruvate NAD + MITOCHONDRION Transport protein NADH + H + Coenzyme ACO 2 Acetyl Co A

13. Krebs Cycle – Big Picture The Krebs Cycle takes place in the mitochondrial matrix, where there is plenty of room for all of the intermediate molecules and enzymes. The main goal is to produce as many NADH and FADH 2 as possible, from each Acetyl Coenzyme A molecule that enters the cycle. 6 NADH total, 2 FADH 2 total, 4 CO 2, and 2 ATP are produced.

14. Kreb’s Cycle Simplified

15. Actual Kreb’s Cycle

16. Cellular Respiration Electron Transport Chain

17. Electron Transport Chain BIG PICTURE -The electron transport chain is made up of a series of proteins that work together to move electrons towards Oxygen. Oxygen is the final electron acceptor and is vital to cellular respiration. -Through several redox reactions, the energy from these electrons is used to pump hydrogens across the inner mitochondrial membrane. -By creating a concentration gradient of hydrogens, ATP is made using ATP Synthase.

18. Electron Transport Chain is located on the inner FOLDED membrane The electron transport chain in cellular respiration is located on the inner mitochondrial membrane. This membrane is folded to allow for a HUGE amount of surface area in each mitochondria and many sets of proteins that work as electron transport chains. How does this compare to photosynthesis?

19. Overview of Electron Transport Chain Protein complex of electron carriers H+H+ ATP Glycolysis Oxidative phosphorylation: electron transport and chemiosmosis Citric acid cycle H+H+ Q III I II FAD FADH 2 + H + NADH NAD + (carrying electrons from food) Inner mitochondrial membrane Inner mitochondrial membrane Mitochondrial matrix Intermembrane space H+H+ H+H+ Cyt c IV 2H + + 1 / 2 O 2 H2OH2O ADP + H+H+ ATP synthase Electron transport chain Electron transport and pumping of protons (H + ), Which create an H + gradient across the membrane P i Chemiosmosis ATP synthesis powered by the flow of H + back across the membrane Oxidative phosphorylation NADH = 3 ATP FADH 2 = 2 ATP *Look at where electrons are dropped off*

20. ATP Synthetase Complex using kinetic movement of H+ (protons)

21. Cellular Respiration Fermentation

22. Anaerobic Respiration Up to this point, we have been discussing aerobic respiration (cellular respiration that occurs in the presence of oxygen). However, organisms can also produce small amounts of ATP through anaerobic respiration as well. Fermentation is a process that is centered around recycling electron carriers so that at least glycolysis can continue. Glycolysis needs NAD+ to function, so by doing this, the organism can produce enough ATP to stay alive.

23. Alcohol Fermentation Bacteria and Yeast In alcohol fermentation, the pyruvates are ultimately converted into Ethanol, by removing CO 2 and bonding Hydrogens in their place. This helps to recycle NADH/NAD+ so that glycolysis can continue. 2 ATP are produced for each glucose molecule and ethanol is the end product.

24. Lactic Acid Fermentation Animals such as yourself – Muscle Cramps! In lactic acid fermentation, the pyruvates are ultimately converted into Lactate/Lactic Acid, by removing one of the Oxygen double bonds and adding Hydrogens. This helps to recycle NADH/NAD+ so that glycolysis can continue. 2 ATP are produced for each glucose molecule and lactic acid is the end product.