1. Cellular Respiration

2. What is Cellular Respiration? Cellular respiration is a catabolic pathway in which oxygen is consumed along with organic fuel. In eukaryotic cells, Mitochondria are the site of cellular respiration Cellular respiration is similar to the combustion of gasoline Food is the fuel for cellular respiration

4. How do Mitochondria perform cellular respiration? By Redox reactions and the recycle of ATP Redox reactions Reactions where electrons transfer from one reactant to another they are said to be oxidation- reduction reactions Loss of electrons- oxidation Gain of electron- reduction

6. Electron transport chains The fall of electrons in the ETC is an exergonic reaction in that it is a slow release of the energy The slow release of energy as it falls down the chain allows us to extract as much energy as possible

9. Glycolysis Produces less than a quarter of the chemical energy that is stored in glucose Most of the energy remains in the 2 pyruvate molecules Glycolysis can be done in both aerobic and anerobic conditions Glycolysis is performed in the cytosol of the cell

10. Glycolysis Essential- Glycolysis splits a six carbon sugar into 2-3 carbon sugars which are called pyruvate Process Consists of 10 steps that can be divided into 2 phases Energy- investment phase- Needs ATP Energy- Pay off phase- Puts out 4 ATP, 2 NADH ( electron acceptor), and 2 pyruvate

11. Glycolysis How does Glycolysis form ATP Substrate-level Phosphorylation An enzyme adds a phosphate group from a substrate to ADP to form ATP How does NAD become NADH It is the electron acceptor that accepts extra hydrogen ions at certain points in glycolysis

14. The Krebs Cycle Will only occur if molecular oxygen is present Steps in the process Converts pyruvate into acetyl CoA Acetyl CoA goes through the Krebs cycle and for each one that enters you get out 3 NADH 1 FADH2 2 CO2 1 ATP

15. Krebs Cycle 1 st step Pyruvate is converted into acetyl CoA This done through a multi-enzyme complex that catalyses 3 reactions Once this process has occurred the Krebs cycle is ready to begin

16. Figure 9.10 Conversion of pyruvate to acetyl CoA, the junction between glycolysis and the Krebs cycle

17. Krebs Cycle Free NADH and FADH 2 !!!!!!! The cycle has 8 steps and each one catalyzed by a specific enzyme in the mitochondrial matrix Each turn of the wheel in the cycle is being catalyzed by a different enzyme Products for each Acetyl CoA 3 NADH 1 FADH2 2 CO2 1ATP For each glucose molecule double the #

19. Figure 9.11 A closer look at the Krebs cycle (Layer 4)

20. Electron Transport Chain and Oxidative Phosphorylation Located in the inner membrane of the mitochondrial matrix Folding of the inner membrane maximizes the SA Chain is made of proteins, 1 lipid, and cytochrome complexes NADH and FADH2 are what supply the e- at the top and middle of chain to start the exergonic fall

22. Electron Transport Chain and Oxidative Phosphorylation As the e- fall down the chain H+ are pumped across the membrane into the inter-membrane space which creates a H+ gradient H+ then fall back from the inter- membrane space to the mitochondrial matrix through ATP synthase which produces ATP This is just like photosynthesis!!!!!

23. Figure 9.13 Free-energy change during electron transport

27. Fermentation Allows some cells to produce ATP without the use of oxygen When cells are in an anaerobic condition they can still produce some ATP through either alcohol fermentation lactic acid fermentation In order for glycolysis to continue working NADH must be oxidized back into NAD so it can be used again

28. Alcohol fermentation Many bacteria and yeast carry out alcohol fermentation Pyruvate is converted into ethanol in two steps Pyruvate releases CO2 and is converted into acetaldehyde Acetaldehyde is reduced by NADH to ethanol This regenerates the supply of NAD Used in winemaking, brewing, and baking

29. Figure 9.17a Fermentation

30. Figure 9.x2 Fermentation

31. Lactic Acid Fermentation Pyruvate is reduced directly by NADH to form lactate with no release of CO2 Done by some fungi and bacteria and is used in the dairy industry to make cheese and yogurt. Human muscle cells make ATP by lactic acid fermentation when O2 is scarce Occurs during the early stages of exercise when your body is breaking down more sugar for ATP than the O2 that you are breathing in

32. Figure 9.17b Fermentation

34. Feedback mechanisms Cellular respiration is controlled by feedback mechanisms The breakdown of glucose will be determined by what your body needs Phosphofructokinase is said to be the controller of cellular respiration because it is an allosteric enzyme that can regulate glycolysis

35. Figure 9.20 The control of cellular respiration

36. Figure 9.19 The catabolism of various food molecules