1. AP Biology: Ch. 9 Cellular Respiration

2. Principles of Energy Conservation As open systems, cells require outside energy sources to perform cellular work. Energy flows into most ecosystems as sunlight, which is used by producers to make food.

4. Fermentation Fermentation is an ATP-producing catabolic pathway in which both electron donors and acceptors are organic compounds. Anaerobic process (does not require oxygen) Results in the partial degradation of sugars

6. Large-scale fermentation at a winery

8. Cellular Respiration ATP-producing catabolic process in which the ultimate electron acceptor is an inorganic molecule, such as oxygen. Most prevalent and efficient catabolic pathway. Begins with glycolysis, includes the Kreb cycle and electron transport chain (ETC). Exergonic process (releases energy).

10. Cellular Respiration: Equation Summarized as: Reactants: C 6 H 12 O 6 + 6 O 2  Reactants: C 6 H 12 O 6 + 6 O 2  Products: 6 CO 2 + H 2 O + energy (ATP + heat) (ATP + heat)

11. ATP: Adenosine triphosphate

12. Oxidation/Reduction Reaction (Redox) Reactions that involve the partial or complete transfer of one or more electrons from one reactant to another. Because an electron transfer requires both a donor and an acceptor, oxidation and reduction always go together.

13. Oxidation/Reduction, cont. A reducing agent loses electrons (becomes more positive) and is oxidized. In oxidation, there is a loss of electrons from a substance. An oxidizing agent gains electrons (becomes more negative) and is reduced. Reduction is the addition of electrons to a substance.

14. Oxidation/Reduction, cont. Oxygen strongly attracts electrons and is a powerful oxidizing agent. Chemical energy is released in a redox reaction that relocates electrons closer to oxygen.

15. Methane combustion as an energy-yielding redox reaction

16. Glycolysis Glycolysis occurs in the cytosol (cytoplasm) of the cell. Produces 4 ATP, but requires 2 ATP to convert glucose to 2 glyceraldehyde phosphate molecules, which are then converted to pyruvate. For each molecule of glucose, glycolysis results in a net gain of 2 ATP and 2 NADH.

19. Kreb Cycle Occurs in the mitochondrial matrix. For every turn of the Kreb cycle: 1) 2 C enter in the acetyl fragment of Acetyl CoA 2) 2 different C are oxidized and leave as CO 2 3) 3 NADH and 1 FADH 2 are produced. 4) 1 ATP is produced by substrate-level phosphorylation 5) Oxaloacetate is regenerated. **It takes TWO complete turns of the Kreb cycle to completely oxidize one glucose molecule.

21. Electron Transport Chain Glycolysis and the Krebs cycle produce only 4 molecules of ATP per glucose. NADH and FADH 2 produced will provide the energy to begin the electron transport chain. Oxidative phosphorylation uses energy released from the electron transport chain to power ATP synthesis.

23. Pathway of Electron Transport ETC is a series of proteins embedded in the inner mitochondrial membrane. Proteins have groups bound to them. During electron transport, the groups alternate between oxidized and reduced states as they accept and donate electrons. Free energy drops as electrons move down the chain.

26. Chemiosmosis ETC makes no ATP directly, but releases energy used for ATP synthesis. Chemiosmosis is the energy-coupling mechanism that uses energy stored in the form of an H+ gradient (proton-motive force) across the membrane to drive cellular work. ATP synthase uses this energy to make ATP from ADP + Pi

28. Maintaining the H+ Gradient The ETC pumps H+ from the mitochondrial matrix, across the inner membrane, to the intermembrane space. The phospholipid bilayer is impermeable to H+, so ions are not allowed to diffuse back in. ATP synthase uses potential energy stored in the proton gradient to make ATP. H+ is allowed to diffuse through the ATP synthase complex, causing the phosphorylation of ADP.

31. Versatility of Catabolism Respiration can oxidize organic molecules other than glucose to form ATP. Carbohydrates, proteins, and fats in the diet are hydrolyzed to form intermediate compounds that enter glycolysis or the Kreb cycle. Fats provide twice the energy per gram as carbohydrates.