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Chapter 9: Cellular Respiration 9-1 Chemical Pathways.

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Presentation on theme: "Chapter 9: Cellular Respiration 9-1 Chemical Pathways."— Presentation transcript:

1 Chapter 9: Cellular Respiration 9-1 Chemical Pathways

2 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

3 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

4 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 = 1,000 calories

5 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

6 Overview of Cellular Respiration 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

7 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)

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

9 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

10 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

11 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

12 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

13 9-2 The Krebs Cycle and Electron Transport

14 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.

15 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

16 ____ The Krebs Cycle The Krebs Cycle Produces (in one turn)

17 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

18 Electron Transport Chain Electrons from NADH and FADH2 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 Virtual Cell ETC Animation H2OH2O NAD  NADH ATP HH HH Controlled release of energy for synthesis of ATP Electron transport chain 2 O2O2 2e   1 2

19 Chemiosmosis In chemiosmosis, the H + diffuses back through the inner membrane through ATP synthase complexes. Driving 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

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

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

23 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 and wine _______ + _____ → __________ + ______ + _____ PYRUVIC ACID ALCOHOLCO 2 NAD +

24 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 + _______ + _____ → ______________ + ________

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

27 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

28 Respiration Questions In your group: 5. See if you can write the chemical equation for respiration (inputs and outputs) 6. What is the organelle in cells that is “releasing” energy during respiration? 7. What primary molecule is energy being “released” from? 8. How is the sun indirectly involved in respiration?

29 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?

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

31 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


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