P2.5 5.Consider the oxidation of a mole of NADH using the following half reactions:12 O2 + 2 e + 2 H+ → H₂ONAD + 2 e + H+ → NADHE = 0.83 VE" = -0.32 Va) Determine E" and AG" for the oxidation of a mole of NADH by oxygen. Show all work forthe calculation of both values and write out the overall reaction.b) Assume that this occurred in a mitochondria with a defective complex IV that resulted inno proton pumping at complex IV (all other complexes pumped protons in their normalfashion). How many moles of protons are pumped as a result of the oxidation of a mole ofNADH using this slightly defective electron transport chain?c) If all of the protons calculated above could be used for ATP production by themitochondrial ATP synthase, how many moles of ATP could be produced?d) If the AG for ATP synthesis is about 50 kJ/mol, what percentage of the energy fromNADH oxidation is captured in ATP formation?

∆G'0 = -nF∆E'0 here; ∆G'0 is the change in standard Gibbs free energy. 'n' is the number of…

Answered: Consider the oxidation of a mole of…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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Similar questions

Discuss the relationship between redox potentials E0’ and the organization of the components of the electron transport chain. Be specific, i.e., use data/actual values to back up your discussion. a) What are the values of E0’ for all the components of the ETS? b)How are the E0’ related to ∆G values? c) How do the values of E0’ vary among the participants in the ETS relative to their position in the ETS?
Below are the reduction reactions for oxygen and FAD. ½202 + 2e + 2H+ → H20 E°' = 0.83 V FAD + 2e + 2H* → FADH2 E" = -0.22 V What is the potential (E") for the oxidation of FADH by oxygen? What is the AG®' for the oxidation of FADH, by oxygen? If we assume that the pumping of protons in conjunction with the oxidation of FADH, requires 120 kJ, what percentage of the energy from FADH oxidation is stored in the proton gradient (think about how many protons are pumped when FADH, transfers electrons to oxygen)?
1. Cyanide, oligomycin, and 2,4-dinitrophenol are all inhibitors of oxidative phosphorylation in mitochon- dria. Provide an explanation to the following conditions regarding these potent inhibitors. (a) Explain why adding cyanide to an active in vitro suspension of mitochondria blocks ATP synthesis. What happens to the rate of ATP synthesis when 2,4-dinitrophenol is added to this mitochon- drial suspension after it was treated with cyanide? (b) Explain why the rate of oxygen consumption decreases in an in vitro suspension of mito- chondria when oligomycin is added. What happens to the rate of oxygen consumption in this oligomycin- inhibited system after adding 2,4-dinitrophenol? Explain.
When pure reduced cytochrome c is added to carefully prepared mitochondria along with ADP, P, antimycin A, and oxygen, the cytochrome c becomes oxidized, and ATP is formed, with a P/o ratio approaching 1.0. (a) Indicate the probable flow of electrons in this system. (b) Why was antimycin A added? (c) What does this experiment tell you about the location of cou- pling sites for oxidative phosphorylation? (d) Write a balanced equation for the overall reaction (including cyt c oxidation and ATP synthesis).
(a) Consider the oxidation of malate to oxaloacetate by NAD*: malate + NAD+ → oxaloacetate + NADH + H+ In yeast mitochondria, where the pH = 8.1, this reaction is exergonic only at low oxaloacetate concentrations. Assuming a pH = 8.1, a temperature of 37 °C, and the steady-state concentrations given below, calculate the maximum concentration of oxaloacetate at which the reaction will still be exergonic. malate + NAD*→ oxaloacetate + NADH + H* lactate + NAD →→ pyruvate + NADH + H+ half reaction Pyruvate + 2H+ + 2e → lactate Pyruvate + CO₂ + H + 2e → malate Intracellular steady state concentrations: malate = 410 μM; NAD = 20.0 mM; pyruvate = 3.22 mM; NADH = 290 μM; AG=+29.7 kJ/mol AG¹ = +25.1 kJ/mol E° (V) - 0.190 - 0.330 lactate 1.1 mM CO₂ = 15.5 torr
3. The succinate dehydrogenase reaction in the direction it proceeds within the CAC is shown below (left to right): FAD FADH, H-C-H H-C-H coo- succinate dehydrogenase Succinate Fumarate AG" - O kl/mol a) Calculate the standard reduction potential for the overall reaction above. b) Based on the reduction potential, calculate and compare your standard transformed free energy change to the textbook value (above), and venture to explain any discrepancies. c) Assuming the temperature of the cell is 37 °C, calculate the equilibrium ratio of oxidized to reduced cofactor when the ratio of oxidized product to reduced substrate is 1.2. .
Shown below are reduction potentials for four half-reactions. Which of the coupled reactions is favorable? (Note that for Cytochrome c you must multiply the reduction potential by 2 for each coupled reaction because only one electron is involved) a) 2 Cytochrome c (Fe3+) + H2O ó 2 Cytochrome c (Fe2+) + O2 b) NADH + Succinate- ó NAD+ + Fumarate- c) Fumarate- + H2O ó Succinate- + O2 d) All of the above
1. Name and draw diagrammatically the series of mitochondrial electron transfer catalysts, starting with the oxidation of NADH and succinate and ending with the reduction of O2. 2. Indicate the sites and stoichiometry (per 2e) at which protons are translocated from the matrix to the intermembrane space. 3. Indicate which complexes are inhibited by: amytal, antimycin A, azide (N3 ), cyanide (CN), carbon monoxide (CO), and rotenone. 4. Describe the effects of (1) oligomycin and (2) uncouplers of oxidative phosphorylation, e.g., dinitrophenol (DNP), carbonyl cyanide-p- trifluoromethoxyphenylhydrazone (FCCP), on respiration and ATP synthesis when added to a suspension of mitochondria with excess malate, ADP, and inorganic phosphate (Pi).
The standard free energy variation of the ATP hydrolysis reaction is ΔGº’ = -30.5 kJ / mol ATP + H2O ⇄ ADP + Pi In red blood cells, when the concentration of Pi is 1.6 mM, the real change in energy free is ΔG = - 50'2 kJ / mol. a) Calculate under these conditions what is the ratio [ATP] / [ADP] in the red blood cells. b) Determine the equilibrium constant K 'of the reaction outlined above. c) If the ADP concentration were 0.2mM, what would be the effective concentration of ATP corresponding to equilibrium.
7) The following questions apply to glycolysis (figure 3-41 on page 79 of the 12th edition), the Krebs cycle (figure 3-44 on page 82) and to oxidative phosphorylation (figure 3-45 on page 84). Calculate the total amount of ATP produced from one glucose molecule if: a. The oxidation of NADH + H* to NAD* + 2H* produced 4 ATP. b. The oxidation of FADH₂ to FAD + 2H* produced 1 ATP. c. Each step of the Krebs cycle that produces NADH+H* produced FADH2 instead. d. Each step of the Krebs cycle that produces FADH2 produced NADH + H+ instead. e. Sucrose is substituted for glucose.
Indicate whether each of the following changes represents oxidation or reduction. Write: O = for oxidation ; R= for reduction Example: cyt ci (Fet) → cyt c1 (Fe2+) Answer: R Blank #1: COQH2 → CoQ Blank #2: NAD+ - NADH Blank #3: FMN → FMNH2 Blank # 4: FADH2 FAD Blank #5: Fe(III) SP → Fe(II) SP Blank # 1 Blank # 2
Two biochemistry students are about to usemitochondria isolated from rat liver for an experiment on oxidative phosphorylation. The directions for the experiment specifyaddition of purified cytochrome c from any source to the reactionmixture. Why is the added cytochrome c needed? Why does thesource not have to be the same as that of the mitochondria?

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