2. Inroduction to Cellular Respiration Open systems need energy from outside sources. Living organisms are open systems Photoautotrophs(pl ants) capture the suns energy and convert it to chemical energy in the form of organic molecules through anabolic reactions.

3. Organic Molecules Organic molecules are burned in the presence of O 2. Some of the chemical energy is used to make ATP which is utilized for cellular work. For example, the oxidation of glucose (a catabolic reaction) provides the energy to produce ATP.

4. Cellular Respiration The the break down of glucose to CO 2 and H 2 O The energy released is trapped in the form of ATP for use in all energy consuming activities of the cell This process occurs in two phases

5. Glycolysis The first phase is called glycolysis Occurs in the cytoplasm Is an anaerobic process Involves the breakdown of glucose to pyruvic acid. The intermediates are oxidized. Two ATPs produced by substrate level phosphorylation

6. Krebs Cycle Occurs in the mitochondrial matrix Intermediate step between glycolysis and Krebs cycle removes a carboxyl group from pyruvic acid to produce aceytl CoA. Acetyl CoA then enters the Krebs cycle to be oxidized to CO 2 and H 2 O. The electrons transferred from the intermediates in the Krebs cycle go the the ETC to make most of the ATP in cellular rerspiration.

8. Fermentation Pyruvic acid will only be converted to acetyl CoA if oxygen is present. I f there is no oxygen pyruvate does not enter the mitochondria. Fermemtation occurs and pyruvate is either reduced to lactic acid or ethanol. The function of fermentation is restore the oxidized form of NAD +.

9. ATP Energy yielded from hydrolysis of ATP is used to transfer phosphates from one molecule to another through enzymes. The phosphorylated molecule does work for the cell. ATP is replenished through cellular respiration.

10. ATP Made in Two Ways Oxidative Phosphorylation Uses electron transport chain to create a proton gradient across the inner mitochondrial membrane. Substrate Level Phosphorylation Transfer of a phosphate group from an intermediate to ADP to make ATP

11. Complexes function in cellular respiration NADH Dehydrogenase pumps protons into the inner membrane space to create a gradient. Succinate Dehydrogenase oxidizes succinate. Cytochrome c redcutase transfers electrons to cytochrome c oxidase. Cytochrome c oxidase transfers electrons to 1/2O 2 to form H 2 O. ATP Synthase phosphorylates ADP to ATP as protons diffuse back across the inner mitochondrial membrane

12. Chemiosomosis The coupling of the exorgonic flow of electrons from the oxidation of food to endergonic ATP production. Proton gradient is created across the inner mitochondrial membrane As protons diffuse back across the membrane ADP is phosphorylated to ATP

13. Oxidative Phosphorylation a Closer Look Highly electronegative O 2 pulls e - down the ETC towards a lower energy state. The e - are harvested from glycolysis and the Krebs cycle. This exorgonic slide of e - is coupled to ATP synthesis For each molecule of glucose oxidized to CO 2 and H 2 O, 36- 38 ATPs are made.

14. REDOX REACTIONS Oxidation- reduction reactions invovle the partial or complete transfer of e- from one reactant to another. Oxidation is the complete or partial loss of e -. Reduction is the partial or complete gain of e-

15. Redox Reactions Electron transfer requires both a donor and and an acceptor. Not all redox reactions involve the complete transfer of e -, but instead, may change the degree of sharing.

16. Respiration and redox Reactions Valence e - of carbon and hydrogen lsoe potential energy as they shift toward electronegative oxygen. Released energy is used to make ATP Organic molecules rich in carbon- hydrogen bonds are excellent fuels. A mole of glucose yields 686 Kcal when burned In cellular respiration, glucose is graduallly oxidized in a series of enzyme controlled steps during glycolysis and the Krebs cycle.

17. NAD + and FAD Hydrogens stripped from glucose are not passed directly to oxygen. They are first passed to NAD + or FAD. NAD + and FAD act as odidizing agents trapping energy rich e- from food molecules. These reactions are catalyzed by dehydrogenases. XH 2 + NAD + --------------X + NADH + H + Dehydrogenases take 2 hydrogen atoms molecule being oxidized. Two e - and 1 proton are delivered to NAD + to produce NADH. The extra proton is released into the sourounding solution.

18. NAD + and the ETC NADH then drops off electrons to the ETC which regenerates NAD +. FAD picks up 2 hydrogen atoms to become FADH 2. For every NADH that makes a trip to the ETC 3 ATP’s are made through chemiosomosis. For every FADH 2 that makes a trip to the ETC 2 ATP’s are made through chemiosomosis