1. CELLULAR RESPIRATION CHAPTER 9 9-1 Chemical Pathways

2. Chemical Energy and Food The two equations are exact opposites! PHOTOSYNTHESIS ___________ + _________ + ___________ → _______________ + __________ 6 CO 2 6 H 2 OC 6 H 12 O 6 6O 2 _____________ + _________ → ________ + __________ + __________ CELLULAR RESPIRATION C 6 H 12 O 6 6O 2 6 CO 2 6 H 2 O

3. Comparing Photosynthesis & Cellular Respiration: Which type(s) of organisms carry out photosynthesis? AutotrophHeterotroph Which type(s) of organisms carry out cellular respiration? AutotrophHeterotroph

6. Overview of Cellular Respiration Cellular respiration is the process that releases energy from food in the presence of oxygen. If oxygen is available, organisms can obtain energy from food by a process called cellular respiration. The summary of cellular respiration is presented below. 6 O 2 + C 6 H 12 O 6  6 CO 2 + 6 H 2 O + Energy (ATP)

7. Structure of the Mitochondria:

9. Chemical Energy and Food Cellular respiration happens slowly and in many steps. If all the energy was release in one step… Most would be lost as light and heat! Cellular respiration breaks down glucose molecules and banks their energy in ATP

10. Chemical Energy and Food Amount of heat it takes to raise 1 gram of water 1 o Celsius = calorie Unit for measuring energy in food = Calorie 1 Calorie = 1 kilocalorie = 1,000 calories

11. Comparing Photosynthesis & Cellular Respiration PhotosynthesisCellular Respiration Function Location Reactants Products Produces food (chemical energy) for the plant (glucose C 6 H 12 O 6 ) Produces chemical energy (ATP) for the cell ChloroplastMitochondria Water (H 2 O), Carbon dioxide (CO 2 ) and sunlight Oxygen (O 2 ) and Glucose (C 6 H 12 O 6 ) Oxygen (O 2 ) and Glucose (C 6 H 12 O 6 ) Water (H 2 O), Carbon dioxide (CO 2 ) and energy (ATP) Energy Consumption - Virtual Cell Animation (4:41)

12. NADH FADH 2 GLYCOLYSIS Glucose Pyruvate CITRIC ACID CYCLE OXIDATIVE PHOSPHORYLATION (Electron Transport and Chemiosmosis) Substrate-level phosphorylation Oxidative phosphorylation Mitochondrion and High-energy electrons carried by NADH ATP CO 2 Cytoplasm Substrate-level phosphorylation Compare Photosynthesis to Cellular Respiration Light Energy CO 2 H2OH2O Chloroplast LIGHT REACTIONS (in thylakoids) CALVIN CYCLE (in stroma) NADP + ADP + P ATP NADPH O2O2 Sugar (C 6 H 12 O 6 ) Electrons How Cells Obtain Energy (14 min)

13. An Overview of Cellular Respiration:

14. Stages of Cellular Respiration The three main stages of cellular respiration are 1. Glycolysis 2. Krebs cycle 3. Electron transport chain.

15. Oxygen and Energy Glycolysis is an ANAEROBIC processes. It does not directly require oxygen, nor does it rely on an oxygen-requiring process to run. Glycolysis is still considered part of cellular respiration. Glycolysis takes place in the cytoplasm of a cell. Glycolysis Overview - Virtual Cell Animation (3:00)

16. Oxygen and Energy Pathways of cellular respiration that require oxygen are called AEROBIC. The Krebs cycle and electron transport chain are both aerobic processes. Both processes take place inside the mitochondria. Citric Acid Cycle An Overview (3:17) Electron Transport Chain (3:48)

17. Overview of Cellular Respiration Occurs in three main stages: Stage 1: Glycolysis Occurs in the cytoplasm Breaks down glucose into pyruvate, producing a small amount of ATP Stage 2: The Citric Acid Cycle (Krebs cycle) Takes place in the mitochondria Completes breakdown of glucose, produces a small amount of ATP Provides third stage of cell respiration with electrons Stage 1 Stage 2 Stage 3

18. Overview of Cellular Respiration Stage 3: Oxidative phosphorylation (ETC) Occurs in the mitochondria Uses the energy released by “falling” electrons to pump H + across a membrane Harnesses the energy of the H + gradient through chemiosmosis, producing ATP Stage 3

19. Understanding Oxidation and Reduction Oxidation is the loss of electrons; electrons are removed from hydrogen atoms contained in glucose. Reduction is the gain of electrons; oxygen atoms accept hydrogen and electrons forming water H 2 O. Remember: OIL RIG (Oxidation Is Loss, Reduction Is Gain) LEO the lion goes GER (Lose Electrons – Oxidation) (Gain Electrons – Reduce)

20. Electron Carriers (enzymes) Involved NAD + (Nicotinamide adenine dinucleotide) Accepts H+ to become NADH FAD (Flavin adenine dinucleotide) Accepts 2H+ to become FADH 2

21. Overview of Cellular Respiration NADH FADH 2 GLYCOLYSIS Glucose Pyruvate CITRIC ACID CYCLE OXIDATIVE PHOSPHORYLATION (Electron Transport and Chemiosmosis) Substrate-level phosphorylation Oxidative phosphorylation Mitochondrion and High-energy electrons carried by NADH ATP CO 2 Cytoplasm Substrate-level phosphorylation Stage 1 Stage 2 Stage 3 Krebs

22. 9.2 Glycolysis (Glykos = sweet, Lysis = split apart) The first step in cellular respiration = Glycolysis Happens in the CYTOPLASM outside the mitochondria Does not require oxygen, BUT it needs some energy to get it started. What molecule is going to supply the energy? ATP

23. Glycolysis PUT IN 2 ATP and GET BACK 4 ATP Net gain of 2 ATP and 2 NADH ________ ↓ ___________ → → _____________ ↓ ____________________ + _______________ GLUCOSE ATP ATP NADH 2 PYRUVIC ACID

24. Glycolysis Produces pyruvic acid (pyruvate – a 3 carbon compound) Cell needs to invest some energy to get a higher return (2 ATP gained) Occurs quickly, in miliseconds to respond to increased energy demand Glycolysis Reactions - Virtual Cell Animation (5:00)

25. 9-2 The Krebs Cycle and Electron Transport

26. Mitochondria Structure Has a double membrane, with an intermembrane space between the two layers. Cristae are folds of the inner membrane The matrix is the innermost compartment, which is filled with a gel-like fluid. Krebs Cycle occurs in the matrix of the mitochondria.

27. The Krebs Cycle Carbon dioxide is lost to the atmosphere as waste ATP can be used directly to supply energy for the cell High energy electron carriers move into the ELECTRON TRANSPORT CHAIN

28. The Krebs Cycle During the Krebs cycle, the 2 nd stage of cellular respirationpyruvic acid produced in glycolysis is broken down into carbon dioxide in a series of energy- extracting reactions. The Krebs cycle is also known as the citric acid cycle because citric acid is the first compound formed in this series of reactions.

29. The Krebs Cycle Pyruvic acid enters the mitochondria matrix Pyruvic acid is converted into an intermediate 2 carbon molecule called Acetyl-CoA before entering the Krebs Cycle. The Krebs cycle breaks down carbon compounds into carbon dioxide (waste), ATP, NADH, and FADH 2 The Citric Acid Cycle The Reactions (4:13)

30. The Krebs Cycle Pyruvic acid from glycolysis enters the matrix, the innermost compartment of the mitochondrion.

31. Kreb’s Cycle Pyruvic acid from glycolysis enters the matrix NAD + accepts 2 high- energy electrons to form NADH. One molecule of CO 2 is also produced. The remaining 2 carbon atoms react to form acetyl- CoA. Diagram by Riedell

32. The Krebs Cycle The Citric Acid Cycle The Reactions (4:13) Acetyl-CoA combines with a 4-carbon molecule (oxaloacetic acid) to produce citric acid.

33. The Krebs Cycle Citric acid is broken down into a 5-carbon compound and then a 4-carbon compound. Two molecules of CO 2 are released. The 4-carbon compound can then start the cycle again by combining with acetyl-CoA. The Citric Acid Cycle The Reactions (4:13)

34. KREBS CYCLE Krebs Cycle AnimationKrebs Cycle Animation-(select #3) 3 1 1 4 KREBS CYCLE PRODUCES ____

35. Electron Transport Chain Enzymes (protein complexes) for the electron transport chain are located on the inner mitochondrial membrane. Several complexes are called cytochromes. Electron Transport Chain (3:48)

36. Electron Transport Chain Electrons from NADH and FADH 2 travel down the electron transport chain, between protein complexes to oxygen (final electron acceptor), which picks up H + to form water Energy released by the redox reactions is used to pump H + into the space between the mitochondrial membranes H2OH2O NAD  NADH ATP HH HH Controlled release of energy for synthesis of ATP Electron transport chain 2 O2O2 2e   1 2 Electron Transport Chain (2:00)

37. Chemiosmosis In chemiosmosis, the H + diffuses back through the inner membrane through ATP synthase complexes. Drives the synthesis of ATP Intermembrane space Inner mitochondrial membrane Mitochondrial matrix Protein complex Electron flow Electron carrier NADH NAD + FADH 2 FAD H2OH2O ATP ADP ATP synthase H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+  P O2O2 Electron Transport Chain Chemiosmosis. OXIDATIVE PHOSPHORYLATION + 2+ 2 1 2

39. Fermentation Pyruvic acid moves to the next step If there is no oxygen = anaerobic If there is oxygen = aerobic

40. Fermentation Fermentation – process by which cells release energy in the absence of oxygen Two types of fermentation: Alcoholic Fermentation Lactic Acid Fermentation

41. Alcoholic Fermentation Happens when yeast makes bread dough rise, CO2 bubbles make air spaces in bread. (Alcohol evaporates during cooking) Happens when: Yeast make beer Bacteria make wine _______ + _____ → __________ + ______ + _____ PYRUVIC ACID ALCOHOLCO 2 NAD +

42. Lactic Acid Fermentation Happens in muscles during exercise when body can’t get oxygen to tissues fast enough. Lactic acid builds up in muscles causing soreness. Bacteria use lactic acid fermentation to make: yogurt, cheese, sour cream, pickles, sauerkraut, kimchi PYRUVIC ACID LACTIC ACIDNAD + _______ + _____ → ______________ + ________

44. The Totals Cellular Respiration (aerobic: with oxygen) 1 glucose → 36 ATP Fermentation (anaerobic: without oxygen) 1 glucose → 2 ATP

45. Respiration Questions 1. List the reactants and products of respiration 2. List the three steps (stages) involved in respiration 3. Name two electron carriers involved 4. What step produces the most ATP

46. Respiration Questions In your group: 1. See if you can write the chemical equation for respiration (inputs and outputs) 2. What is the organelle in cells that is “releasing” energy during respiration? 3. What primary molecule is energy being “released” from? 4. How is the sun indirectly involved in respiration?

47. Fermentation Questions 1. List two types of fermentation 2. List the reactants for both types of fermentation 3. List the products for fermentation used to brew beer 4. List the products for fermentation used to make yogurt 5. What important molecule cycles back from fermentation to keep glycolysis going? 6. What process starts fermentation?

48. Krebs Cycle 1.___________ 2.___________ 3.________ 4.________ 5.________6.________ 7.________

49. Electron Transport Chain (ETC) Intermembrane space Inner mitochondrial membrane Mitochondrial matrix Protein complex Electron flow Electron carrier NADHNAD + FADH 2 FAD H2OH2O ATP ADP ATP synthase H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+  P O2O2 Electron Transport Chain Chemiosmosis. OXIDATIVE PHOSPHORYLATION + 2+ 2 1 2

50. Cellular Respiration - Glycolysis, Krebs Cycle, ETC (6:00)