What terms would best describe the above coupled reaction? (If the DGo for ATP hydrolysis into ADP + inorganic phosphate is -7.3 kcal/mole, and the DGo for maltose synthesis from glucose + glucose is +3.7 kcal/mole, calculate the standard free energy change for the combined reaction of ATP + glucose + glucose g ADP + maltose + inorganic phosphate.) it is non-spontaneous and endothermic (because the overall DGo is negative) it is spontaneous and exothermic (because the overall DGo is negative) it is non-spontaneous and endothermic (because the overall DGo is positive) it is spontaneous and exothermic (because the overall DGo is positive) it is non-spontaneous and exothermic (because the overall DGo is negative)

For part (b) of this problem, use the following standard reduction potentials, free energies, and nonequilibrium concentrations of reactants and products: Consider the last two steps in the alcoholic fermentation of glucose by brewer’s yeast:                                                                        pyruvate + NADH + 2H+ → ethanol + NAD+ + CO2 (a) Do you predict that ∆S° for this reaction is > 0 or < 0? (b) Calculate the nonequilibrium concentration of ethanol in yeast cells, if ∆G = -38.3 kJ/mol for this reaction at pH = 7.4 and 37 °C when the reactants and products are at the concentrations given above. (c) How would a drop in pH affect ∆G for the reaction described in part (b)? (d) How would an increase in intracellular CO2 levels affect ∆G for the reaction in part (b)? (e) How would an increase in intracellular CO2 levels affect ∆G°′ for the reaction in part (b)?

Given the following reaction and equation for the initial velocity of the reaction: k₁ k3 E+S ES E + P V=Keat [ES] = k3 [ES] k₂ where keat is the rate constant for the reaction which forms the product from the ES complex. Explain in words why the velocity is directly proportional to theamount of enzyme added in the presence of saturating substrate levels.

The first reaction in glycolysis is the phosphorylation of glucose to form glucose 6-phosphate: P₁+ glucose glucose 6-phosphate + H₂O This is a thermodynamically unfavorable reaction, with AG° = +13.8 kJ/mol. a) In a liver cell at 37°C the concentrations of both phosphate and glucose are normally maintained at about 5 mM each. What is the equilibrium concentration of glucose 6- phosphate, according to the above reaction? b) This very low concentration of glucose 6-phosphate is unfavorable for glycolysis. In fact, the reaction is coupled to the hydrolysis of ATP: ATP + H₂O2 ADP + P₁ +H* AG°¹ = -32.2 kJ/mol Write the expression for the overall reaction and calculate AG°¹. c) In addition to the glucose and phosphate concentrations listed in part (a) above, assume that the liver cell concentrations of ATP and ADP are 3 mM and 1 mM, respectively. Calculate the theoretical equilibrium concentration of glucose 6-phosphate at pH = 7.4 and 37 °C. C ZOOM +

A total of 30.5 kJ mol-1 of free energy is needed to synthesise ATP from ADP and Pi  when the reactants and products are at 1.0 M concentrations and the temperature is 25oC. Because the actual physiological concentrations of ATP, ADP, and Pi are not 1.0 M, and the temperature is 37oC, the free energy required to synthesise ATP under physiological conditions is actually ~ 46.2 kJ mol-1. A 68 kg adult requires an energy intake of 8,550 kJ of food per day (24 hours). Calculate the mass (in Kg) of ATP synthesised by a human adult in 24 hours, assuming that the percentage efficiency of converting inputted calories in ATP is 50%. What percentage of the body weight does this represent?

The phosphorylation and oxidative decarboxylation of oxaloacetate by inorganic phosphate (Pi) to make phosphoenolpyruvate and carbon dioxide is endergonic under intracellular conditions. It is characterized by this equation:   Oxaloacetate + Pi ←→ Phosphoenolpyruvate + H2O + CO2 ΔG’ = +24.6 kJ/mol   The synthesis of GTP from GDP and inorganic phosphate (Pi) in solution is endergonic under intracellular conditions, and it is characterized by this equation:   GDP + Pi ←→ GTP + H2O ΔG’ = +30.5 kJ/mol   Write a new net thermodynamically coupled reaction equation that describes the synthesis of phosphoenolpyruvate from oxaloacetate using the hydrolysis of GTP to power the reaction and calculate the new net ΔG’ of this reaction. Show all of your work.

Write the coupled reaction that would occur spontaneously for the following pairs of molecules under standard condition: Oxaloaxcetate and NAD+

At what substrate concentration would an enzyme with a kcat of 33.0 s-1 and a Km of 0.0046 M operate at one-tenth of its maximum rate? Assume the enzyme obeys Michaeli s-Menten kinetics.

Consider the two half-reactions below and their standard reduction potentials. NAD+ + H+ + 2e → NADH Elo= -0.32 V a-Ketoglutarate + CO₂ + 2H+ + 2e → Isocitrate E' = -0.38 V (a) What is AE" for the spontaneous redox reaction that is, the reaction that actually occurs under standard biochemical conditions (pH 7)? (b) Which of the following statements are correct under standard biochemical conditions? i. The concentration of H+ is 1.0 M. ii. The reaction NAD+ + Isocitrate → NADH + H+ + a-Ketoglutarate + CO₂ is favor- able. iii. NAD+ accepts electrons from isocitrate. iv. The NAD → NADH reaction actually occurs in reverse. The a-ketoglutarate → isocitrate reaction occurs as written. (c) Calculate AG" for the reaction in (a). (pH 7, 25°C, pressure, 1 atm.) (d) Suppose that the actual conditions are T = 25°C, pH = 7, CO₂ = 1 atm, [a-Ketoglutarate] 10 mM, [NAD+] = 2.5 mM, and [NADH] = 0.5 mM. PAR = 2 mM, [Isocitrate] DE What is the value of AG under those conditions? (Hints: pH 7 is already…

Free energy changes under intracellular conditions differ markedly from those determined under standard conditions. AG" =-30.5 kJ/mol for ATP hydrolysis to ADP and P,. Calculate AG for ATP hydrolysis in a cell at 37 °C that contains [ATP] =3 mM, [ADP] =1mM, and [P] =1 mM.