Energy Conversion Problem 1. a) Influence of concentration on the free energy change. In frog muscle, the concentrations of ATP, ADP, and phosphate are 1.25x10-³ M, 0.50x10-3 M, and 2.50 x10-3 M respectively. Write the reaction and the reaction quotient, Q, for the reaction ATP → ADP + P₁. Calculate the free energy change, AG', for the hydrolysis of ATP in muscle cells given the concentrations given above. Assume that AG"=-31.0 kJ mol-¹ for the hydrolysis of ATP, the temperature is 25°C, and the pH=7. b) For this system, what is the maximum amount of work that can be done per mole of ATP hydrolyzed? c) In muscle, phosphocreatine serves as a carrier of chemical energy. It can transfer its phosphate group to ADP to replenish the ATP used in muscle contraction. This is an example of energy coupling - using the energy of a very favorable reaction to drive an unfavorable reaction. The enzyme creatine phosphokinase catalyzes the reaction: creatine phosphokinase Net rxn creatine + ATP AG"= ???? kJ mol-¹ phosphocreatine + ADP d) Show above how you calculate AG" for the net reaction given that the hydrolysis for phosphocreatine (Phosphocreatine → creatine + Pi) is AG"=-43.1 kJ mol-¹.
Energy Conversion Problem 1. a) Influence of concentration on the free energy change. In frog muscle, the concentrations of ATP, ADP, and phosphate are 1.25x10-³ M, 0.50x10-3 M, and 2.50 x10-3 M respectively. Write the reaction and the reaction quotient, Q, for the reaction ATP → ADP + P₁. Calculate the free energy change, AG', for the hydrolysis of ATP in muscle cells given the concentrations given above. Assume that AG"=-31.0 kJ mol-¹ for the hydrolysis of ATP, the temperature is 25°C, and the pH=7. b) For this system, what is the maximum amount of work that can be done per mole of ATP hydrolyzed? c) In muscle, phosphocreatine serves as a carrier of chemical energy. It can transfer its phosphate group to ADP to replenish the ATP used in muscle contraction. This is an example of energy coupling - using the energy of a very favorable reaction to drive an unfavorable reaction. The enzyme creatine phosphokinase catalyzes the reaction: creatine phosphokinase Net rxn creatine + ATP AG"= ???? kJ mol-¹ phosphocreatine + ADP d) Show above how you calculate AG" for the net reaction given that the hydrolysis for phosphocreatine (Phosphocreatine → creatine + Pi) is AG"=-43.1 kJ mol-¹.
Biochemistry
6th Edition
ISBN:9781305577206
Author:Reginald H. Garrett, Charles M. Grisham
Publisher:Reginald H. Garrett, Charles M. Grisham
Chapter18: Glycolysis
Section: Chapter Questions
Problem 15P
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![Energy Conversion Problem
1. a) Influence of concentration on the free energy change. In frog muscle, the concentrations of ATP, ADP,
and phosphate are 1.25x10-³ M, 0.50x10-³ M, and 2.50 x10³ M respectively. Write the reaction and the
reaction quotient, Q, for the reaction ATP → ADP + P₁. Calculate the free energy change, AG', for the hydrolysis
of ATP in muscle cells given the concentrations given above. Assume that AGº'=-31.0 kJ mol-¹ for the hydrolysis
of ATP, the temperature is 25°C, and the pH=7.
b) For this system, what is the maximum amount of work that can be done per mole of ATP hydrolyzed?
c) In muscle, phosphocreatine serves as a carrier of chemical energy. It can transfer its phosphate group to
ADP to replenish the ATP used in muscle contraction. This is an example of energy coupling - using the
energy of a very favorable reaction to drive an unfavorable reaction. The enzyme creatine phosphokinase
catalyzes the reaction:
Net rxn
phosphocreatine + ADP
creatine phosphokinase
→
creatine + ATP
AG°= ???? kJ mol-¹
d) Show above how you calculate AG" for the net reaction given that the hydrolysis for phosphocreatine
(Phosphocreatine → creatine + Pi) is AGº'=-43.1 kJ mol-¹.
e) Write the equilibrium constant expression and calculate the equilibrium constant of this reaction using
AG⁹¹.
f) As ATP is used, the phosphocreatine stores are depleted. Using the ATP and ADP concentrations given above
in part a, at what ratio of [creatine]/[phosphocreatine] would you expect the reaction to stop (or reach
equilibrium)? Use K from e) and the equilibrium constant expression to solve this problem.
g) Do some research. How does the level of phosphocreatine remain high in muscle cells. Where/how is it
remade from creatine? Look at the enzyme that carries out this reaction. What does it require? How does it
facilitate the coupled reaction? (one paragraph)](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fc687de40-2a04-4618-94c5-bffabbb64b83%2Fee22a515-4cea-4d86-99d7-c67ca6a50811%2F7vxn3a5_processed.jpeg&w=3840&q=75)
Transcribed Image Text:Energy Conversion Problem
1. a) Influence of concentration on the free energy change. In frog muscle, the concentrations of ATP, ADP,
and phosphate are 1.25x10-³ M, 0.50x10-³ M, and 2.50 x10³ M respectively. Write the reaction and the
reaction quotient, Q, for the reaction ATP → ADP + P₁. Calculate the free energy change, AG', for the hydrolysis
of ATP in muscle cells given the concentrations given above. Assume that AGº'=-31.0 kJ mol-¹ for the hydrolysis
of ATP, the temperature is 25°C, and the pH=7.
b) For this system, what is the maximum amount of work that can be done per mole of ATP hydrolyzed?
c) In muscle, phosphocreatine serves as a carrier of chemical energy. It can transfer its phosphate group to
ADP to replenish the ATP used in muscle contraction. This is an example of energy coupling - using the
energy of a very favorable reaction to drive an unfavorable reaction. The enzyme creatine phosphokinase
catalyzes the reaction:
Net rxn
phosphocreatine + ADP
creatine phosphokinase
→
creatine + ATP
AG°= ???? kJ mol-¹
d) Show above how you calculate AG" for the net reaction given that the hydrolysis for phosphocreatine
(Phosphocreatine → creatine + Pi) is AGº'=-43.1 kJ mol-¹.
e) Write the equilibrium constant expression and calculate the equilibrium constant of this reaction using
AG⁹¹.
f) As ATP is used, the phosphocreatine stores are depleted. Using the ATP and ADP concentrations given above
in part a, at what ratio of [creatine]/[phosphocreatine] would you expect the reaction to stop (or reach
equilibrium)? Use K from e) and the equilibrium constant expression to solve this problem.
g) Do some research. How does the level of phosphocreatine remain high in muscle cells. Where/how is it
remade from creatine? Look at the enzyme that carries out this reaction. What does it require? How does it
facilitate the coupled reaction? (one paragraph)
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