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Pathways That Harvest Chemical Energy Energy flows though living systems Sun →→→→ carbohydrate →→→→ ATP →→→→ heat photosynthesis respiration work high energy phosphate bond...

Pathways That Harvest Chemical Energy Energy flows though living systems Sun →→→→ carbohydrate →→→→ ATP →→→→ heat photosynthesis respiration work high energy phosphate bond 2 Energy flows though living systems high energy phosphate bond It’s all about passing electrons around....  Chemical bonds Hydrogen atom \  Electrons and energy shells Energy shell - a discrete distance from the nucleus where electrons have different states of potential energy.  Sun →→→→ carbohydrate →→→→ ATP →→→→ heat photosynthesis respiration work Need to understand: Oxidation and reduction- the loss and gain of electrons, respectively Electronegativity- Oxidation-Reduction (REDOX) Reactions OXIDATION (e- lost) Oxidation: The loss of electron(s) X·e- +Y X + Y·e- Reduction: The gain of electron(s) REDUCTION (e- gained) Oxidizing agent: Oxidizes by accepting electron X·e- + Y X + Y·e- Reducing Oxidizing Reducing agent: Agent Reduces by donating Agent electron  Oxidation-Reduction (REDOX) Reactions H + e- NAD+ Reduction NADH (oxidized form) Oxidation (reduced form) Coenzyme NAD is an electron carrier in redox reactions. Coenzyme NAD is an electron carrier in redox reactions. H + e- NAD+ Reduction NADH (oxidized form) Oxidation (reduced form) - H NAD+ + NADH H + e- Coenzyme NAD is an electron carrier in redox reactions. H + e- NAD+ Reduction NADH (oxidized form) Oxidation (reduced form) - H NAD+ + NADH H + e- - H NAD+ NADH Coenzyme NAD is an electron carrier in redox reactions. Coenzyme NAD and FAD are high energy electron carriers NAD+ Reduction NADH (oxidized form) (reduced form) Oxidation Low P.E High P.E  Oxidation-Reduction (REDOX) Reactions Coenzyme FAD FAD 2H+ + 2e- FADH2 Reduction (oxidized form) (reduced form) Oxidation Coenzyme FAD is an electron carrier in redox reactions.  Sun →→→→ carbohydrate →→→→ ATP →→→→ heat photosynthesis respiration work Need to understand: Oxidation and reduction- the loss and gain of electrons, respectively Electronegativity- the tendency of an atom in one molecule to attract electrons present in another molecule.  Oxidation-Reduction (REDOX) Reactions OXIDATION (e- lost) X·e- +Y X + Y·e- REDUCTION (e- gained) Y is more electro negative than X. As a result, it pools electron from X Which statement correctly describes the relationship between chemical oxidation and reduction? A. A molecule becomes oxidized when it gains a proton. B. A molecule becomes reduced when it gains an electron. C. A molecule acts as a reducing agent when takes an electron from another molecule. D. A molecule acts as an oxidizing agent when it loses an electron to another molecule. Which statement is true concerning the hypothetical reaction shown? (e- represents an electron.) Xe- + Y → X + Ye- A. X is the reducing agent and Y is more electronegative than X. B. X is the reducing agent and is more electronegative than Y. C. X is the oxidizing agent and Y is more electronegative than X. D. X is the oxidizing agent and more electronegative than X. Oxidizing agent: Oxidizes by accepting electron Reducing agent: Reduces by donating electron Glucose + NAD + 2 Pyruvate + NADH In the forward reaction 1. Which molecule is oxidized A 2. Which molecule is reduced C 3. Which molecule is oxidizing agent C 4. Which molecule is reducing agent A 5. Which molecule is more electronegative C A. Glucose B. Pyruvate C. NAD+ D. NADH STOP Oxidation-Reduction (REDOX) Reactions  Cellular respiration Drives ATP Synthesis + 6 O2 HIGH PE ENERGY RELEASE Free Energy 6 CO2 + 6 H20 Progress of Reaction → LOW PE Sun →→→→ carbohydrate →→→→ ATP →→→→ heat photosynthesis respiration work carbohydrate →→→→ ATP →→→→ heat respiration work  carbohydrate →→→→ ATP →→→→ heat respiration work Cellular respiration → energy is released in a regulated manner. Cellular respiration energy is released in a regulated manner.  A Cell CELL MEMBRANE NUCLEUS CYTOPLASM MITOCHONDRIA Respiration is partly occurring in the cytoplasm and partly in the mitochondria.  Cellular respiration Inner mitochondrial Cytoplasm Mitochondrial matrix membrane Mitochondria Mitochondria MATRIX OUTER MEMBRANE INTER MEMBRANE SPACE INNER MEMBRANE Cytoplasm  Glycolysis = I CARBON 1 GLUCOSE 2 PYRUVATE GLUCOSE 2 ATP 2 ADP iP 4 ADP + iP 4 ATP 2 NAD+ 2 NADH PYRUVATE GLYCOLYSIS OCCURS IN THE CYTOPLASM C6H1206 + 2NAD+ 2 Pyruvate + 2NADH + 2ATP Glucose 1. Which molecule is reduced? 2NAD+ 2. Which molecule is oxidized? Glucose  Stage 2: Pyruvate oxidation Pyruvate oxidation is happening in the mitochondrial matrix 2 ACETYL CoA 2 PYRUVATE PYRUVATE 2 Coenzyme A 2 NADH 2 NAD+ 2 CO2 1 CARBON IS LOST AS CO2 COENZYME A ACETYL COENZYME A  2CoA 2 Pyruvate + 2NAD+ 2 Acetyl CoA + 2NADH + 2CO2 1. Which molecule is reduced? 2NAD+ 2. Which molecule is oxidized? Pyruvate Stage 3: Citric acid cycle/ Krebs cycle }X 2 Citric acid cycle is happening in the mitochondrial matrix  ACETYL COA (2C) 2 ACETYL CoA OXALOACETATE (4C) 2 OAA 6 NAD+ 2 FAD NADH 2 ADP +iP NADH 4 CO2 2 OAA 6 NADH 2 FADH2 2 ATP 2 Acetyl CoA + 6NAD+ + 2FAD 4CO2 + 6NADH + 2 FADH2 + 2ATP 1. Which molecule is reduced? 6NAD+ and 2FAD 2. Which molecule is oxidized? Acetyl COA  H+ + 2e- NAD+ Reduction NADH (oxidized form) Oxidation (reduced form) In this reaction, which molecule has more potential energy A. NADH B. NAD+ Why?  Stage 4: Oxidative Phosphorylation At this point, lots of NADH and FADH 2 are generated. NADH and FADH2 have potential energy! Time to cash them in!  Mitochondria NADH NADH NADH NADH NADH FADH2 FADH2 ETC = Electron transport chain is a complex of membrane associated proteins that transport electron from an electron donor (like NADH or FADH2) to a final electron acceptor (like oxygen)  INNER MEMBRANE OUTER MEMBRANE INTER MATRIX MEMBRANE SPACE Electron I transport COMPLEX I chain II COMPLEX II III COMPLEX III COMPLEX IV IV  INNER MEMBRANE OUTER MEMBRANE Electron MATRIX INTER MEMBRANE NADH SPACE transport chain NADH I NADH NADH II FADH2 III FADH2 IV  INNER MEMBRANE OUTER MEMBRANE MATRIX INTER MEMBRANE Electron SPACE transport chain NADH Each time a protein complex e- gains electron, the complex is NAD+ H+ + 2e- reduced. Again, when it loses the election, it is oxidized. FADH2 e- FAD 2H+ 2e- Remember, electrons carry e- energy So, when the protein complex gains electron (with energy), it e- has more energy. When the H+ + O2 complex is oxidized, it releases energy H2O  INNER MEMBRANE OUTER MEMBRANE INTER MEMBRANE MATRIX SPACE Electron NADH transport NAD+ H+ e - chain FADH2 H+ As the protein complex transforms from a FAD 2H+ 2e- reduced high energy H+ intermediate to an oxidized low energy, a part of the energy is used to move protons H+ O2 (H+) from the matrix to the intermembrane space H2O  INNER MEMBRANE OUTER MEMBRANE MATRIX INTER MEMBRANE SPACE Electron NADH H+ transport NAD+ H+ 2e- H+ H+ chain H+ FADH2 H+ H+ H+ FAD 2H+ 2e- H+ H+ H+ H+ H+ A proton (H+) gradient is H+ H+ thus build up across the inner membrane as the H+ H+ O2 ETC transports electron H+ H+ H+ H2O  INNER MEMBRANE OUTER MEMBRANE MATRIX INTER MEMBRANE SPACE ATP I H+ Synthase H+ H+ H+ H+ II H+ H+ H+ H+ III H+ H+ H+ H+ H+ IV H+ + H+ H ATP Synthase H+  ATP Synthase Chemiosmosis- Flow of protons (H+) down the proton gradient through ATP synthase Phosphorylation- IV Synthesis of ATP from ATP Synthase ADP + iP Oxidative Phosphorylation- Electron transport and chemiosmosis  Oxidative phosphorylation Mitochondrial matrix Inter membrane space Electric transport chain Chemiosmosis Oxidative phosphorylation Protons flow through ATP synthase, and the potential energy in the proton gradient is converted to the potential energy found in ATP. When we apply the term “chemiosmosis” to the inner mitochondrial membrane, we are emphasizing which aspect? A. The movement of protons across a selectively permeable membrane from an area of high to low proton concentration. B. More ATP is generated in the electron transport chain than in the other stages of respiration. C. Electron carriers (NADH and FADH2) pass high energy electrons to the electron transport chain. D. Many of the components of the electron transport chain are embedded in the inner mitochondrial membrane. E. ATP synthase can be compared to a mechanical motor in its structure and how it functions. The immediate source of electrons for the electron transport chain is: A. NAD+. B. pyruvate. C. NADH and FADH2. D. H2O. E. O2. Due to the pumping action of the electron transport chain, protons have a high concentration in the _____ and a low concentration in the _____. A. mitochondrial matrix; intermembrane space B. mitochondrial matrix; cytoplasm C. mitochondrial matrix; extracellular fluid D. intermembrane space; mitochondrial matrix The final (terminal) electron acceptor of the electron transport chain is: A. coenzyme Q. B. NAD+. C. oxygen. D. ATP synthase. E. cytochrome c. The pH in the intermembrane space of the mitochondria should be _____ compared with the matrix due to the _____ concentration of protons in the intermembrane space. A. lower; higher B. higher; higher C. higher; lower D. lower; lower What is the source of energy that directly powers ATP production by ATP synthase? A. the energy in electrons from NADH and FADH2 B. the hydrogen ion gradient across the inner membrane C. the ATP produced in glycolysis D. the oxidation and reduction of the electron transport chain E. the movement of hydrogen ions from the matrix to the intermembrane space The energy from the movement of electrons through the electron transport chain is directly used to synthesize ATP. A. True B. False Remember , movement of electrons through electron transport chain creates the proton gradient. It does not make ATP directly. The energy in the proton gradient creates ATP. As protons diffuse back to the matrix via the ATP synthase, ADP and iP (inorganic phosphate) are combined to create ATP When the electron transport chain is operating, the concentration of protons (H+) increases on the outside of the inner mitochondrial membrane, resulting in a concentration gradient that can be used to drive ATP synthesis. Subsequent movement of protons back across the selectively permeable membrane from the area of high concentration to the area of low concentration is called: A. chemiosmosis B. proton pumping C. electron flow D. hydrolysis E. acidification How are the electrons moving during respiration? Which summary sequence correctly tracks electrons through the overall process of aerobic cellular respiration? A. glucose → pyruvate → acetyl‐CoA → carbon dioxide B. glucose → pyruvate → acetyl‐CoA → carbon dioxide → ATP C. glucose → electron carriers → electron transport chain → water D. NAD+ and FAD → NADH and FADH2 → ATP An Accounting of ATP Production by Cellular Respiration Total NaDH= 10 Total FADH2= 2 Total ATP= 4 1 NaDH= 2.5 ATP 10 NaDH= 25 ATP 1 FADH2= 1.5 ATP 2 FADH2= 3 ATP Net ATP produced = about 28-32 In absence of oxygen  ACETYL COA OXALOACETATE NADH NADH Stage 2: Pyruvate oxidation  In absence of oxygen In the presence of oxygen most eukaryotic cell undergo cellular respiration occurs. In the absence of oxygen, those cells go into fermentation.  Alcohol and Lactic Acid Fermentation Alcohol fermentation Lactic acid fermentation Alcohol fermentation happens in yeast. Lactic acid fermentation occurs in mammals. Fermentation help regenerating NAD+ (oxidized electron carrier) to keep carrying out glycolysis and producing the net 2 ATP molecules.  Alcohol fermentation OXIDATION GLUCOSE (e- lost) ACETALDEHYDE ETHANOL REDUCTION (e- gained) PYRUVATE ACETALDEHYDE ETHANOL Lactic acid fermentation OXIDATION (e- lost) GLUCOSE PYRUVATE LACTATE REDUCTION (e- gained) PYRUVATE LACTATE Comparing Fermentation with Aerobic Respiration: Similarities Both use glycolysis to oxidize glucose NAD+ accepts electrons during glycolysis Generates 2 ATP Comparing Fermentation with Aerobic Respiration: Similarities Different mechanisms for oxidizing NADH to NAD+: Fermentation = NAD+ regeneration with final result of ethanol or lactate VS. Cell respiration = electron transport chain Per glucose molecule: Ferm (2 ATP) vs. C.R. (32 ATP)! In absence of oxygen In absence of oxygen Which of the following pathways has NAD+ as an input? A. Glycolysis B. Pyruvate Oxidation C. Citric Acid Cycle D. Fermentation E. A, B, and C Which of the following pathways have NAD+ as an output? A. Glycolysis B. Pyruvate Oxidation C. Citric Acid Cycle D. Fermentation E. None of the above Which of the following pathways require oxygen as an input? A. Glycolysis B. Pyruvate Oxidation C. Citric Acid Cycle D. Oxidative phosphorylation E. Fermentation and glycolysis Which of the following pathways occurs anaerobically? A. Glycolysis B. Pyruvate Oxidation C. Citric Acid Cycle D. Oxidative phosphorylation E. Fermentation and glycolysis Which of the following pathway/pathways occurs in the presence of oxygen? A. Glycolysis B. Pyruvate Oxidation, Citric Acid Cycle and Oxidative phosphorylation C. Citric Acid Cycle D. Oxidative phosphorylation only E. Fermentation and glycolysis Which of the following pathway/pathways requires oxygen as an input? A. Glycolysis B. Pyruvate Oxidation, Citric Acid Cycle and Oxidative phosphorylation C. Citric Acid Cycle D. Oxidative phosphorylation only E. Fermentation and glycolysis How did the earliest organisms on Earth most likely produce ATP? A. by oxidative phosphorylation B. by the citric acid cycle C. by pyruvate oxidation D. by glycolysis  E.T.C As hydrogen ions are moved into the intermembrane space, what happens to the pH in that inter membrane space? A. It becomes more acidic. B. It becomes more basic  E.T.C Which is more electronegative? The electron transport chain creates a proton gradient which is: A. Protein complex I A. Kinetic energy B. NADH B. Potential energy  E.T.C Protons move through ATP Movement of protons through ATP synthase by? synthase is: A. Facilitated diffusion A. Kinetic energy B. Primary active transport A. Potential energy  E.T.C As oxygen combines with protons and electrons to form water it becomes A. Oxidized B. Reduced  In absence of oxygen Without oxygen to accept electrons, we can’t regenerate NAD+ and FAD  In absence of oxygen What would happen to the pH of the matrix in the absence of oxygen? A. It would go down B. It would go up Conditions that reduce the strength of the proton gradient across the inner mitochondrial membrane slow the production of ATP by ATP synthase. true false When oxygen is depleted, the citric acid cycle and pyruvate oxidation stops. What could we add to the system to restore citric acid cycle and pyruvate oxidation activity (other than oxygen)? A. glucose B. acetyl‐CoA C. ADP and Pi D. ethanol and lactic acid E. NAD+ or FAD Oligomycin is an antibiotic that binds ATP synthase, blocking the flow of protons through the enzyme's proton channel. In addition to preventing synthesis of ATP, what additional effect might you expect in response to the presence of oligomycin? A. lower pH in the intermembrane space B. higher pH in the intermembrane space C. a buildup of protons in the mitochondrial matrix Given that the free energy available from the full oxidation of glucose is −686 kcal/mole, which ratio represents the ratio of the free energy captured in ATP by aerobic cellular respiration to the free energy in glucose as the starting fuel molecule? A. 234:686 B. 7.3:686 C. 530:686 D. 53:234 E. 7.3:234 When considering the transfer and capture of potential energy derived from glucose during cellular respiration, which molecule carries the smallest amount of that potential energy? A. NADH B. acetyl‐CoA C. ATP D. pyruvate E. FADH2 Which example represents the reduced forms of the two major electron carriers? NADH and FADH2 NAD+ and FADH2 NADH and FAD NAD+ and FAD Why do some marathon runners attempt to "carbo load" (that is, eat a lot of pasta) before a big race? A. They will feel full longer. B. The bonds in carbohydrates have high potential energy. C. The bonds in carbohydrates have low potential energy and can thus be broken down and readily consumed. D. Through the process of anabolism, the athlete will break down the carbohydrates into smaller components, including ATP. Which of the following summarizes the net final products of glycolysis? A. two molecules of pyruvate, two molecules of ATP, and two molecules of NADH B. four molecules of ATP, four molecules of NADH, and six molecules of CO2 C. two molecules of NADH, two molecules of acetyl-CoA, and two molecules of CO2 D. two molecules of acetyl-CoA, two molecules of pyruvate, and two molecules of ATP Tracing the metabolism of one glucose molecule, how many carbon atoms are available for further oxidation at the completion of the pyruvate oxidation stage? A. 4 B. 2 C. 3 D. 1 E. 5 Once they have been processed through the citric acid cycle, the acetyl‐CoA molecules from a single glucose molecule produce: A. 2 ATP, 6 NADH, 4 CO2, and 2 FADH2. B. 6 NADH and 6 GTP. C. 6 FADH2, 2 ATP, and 6 CO2. D. 6 GTP and 6 FADH2. E. 4 CO2, 6 FADH2, and 2 ATP. In pyruvate oxidation, the electron donor is _____ and the electron acceptor is _____. A. acetyl-CoA; NADH B. pyruvate; NAD+ C. NADH; acetyl-CoA D. NAD+; NADH E. NAD+; pyruvate