Refer to the following equations to answer the questions. 1, 3-bisphosphoglycera
ID: 534196 • Letter: R
Question
Refer to the following equations to answer the questions. 1, 3-bisphosphoglycerate +- H_2O rightarrow 3-phosphoglycerate + HPO^2-_4 -11.8 kcal/mol ATP + H_2O rightarrow ADP + HPO^2-_4 - 7.3 kcal/mol a. Write the equation for the coupled reaction of 1, 3-bisphosphoglycerate with ADP to form 3-phosphoglycerate and ATP. b. Calculate the energy change for this coupled reaction. c. Can this reaction be used to synthesize ATP from ADP? Explain. Refer to the equations in Problem 23.33 to answer the following questions. a. Write the equation for the coupled reaction of 3-phosphoglycerate with ATP to form 1, 3-bisphosphoglycerate and ADP. b. Calculate the energy change for this coupled reaction. c. Is this reaction energetically favorable? Explain.Explanation / Answer
23.34) The given reactions are:
1,3-biphosphoglycerate + H2O -------> 3-phosphoglycerate + HPO42-; E = -11.8 kcal/mol ….(1)
ATP + H2O ------> ADP + HPO42-; E = -7.3 kcal/mol ….(2)
a) We are to couple the reaction between 3-phosphoglycerate and ATP to produce 1,3-biphosphoglycerate and ADP. To do this, reverse (1) and add to (2)
3-phohphoglycerate + HPO42- + ATP + H2O ------> 1,3-biphosphoglycerate + H2O + ADP + HPO42-
Cancel out the common terms and write
3-phosphoglycerate + ATP ------> 1,3-biphosphoglycerate + ADP
b) The energy change for the coupled reaction is the sum of the negative of E for the first reaction (changing the direction of the reaction changes the sign of E) and E for the second reaction.
Ecoupled = -E (1) + E (2) = -(-11.8 kcal/mol) + (-7.3 kcal/mol) = (11.8 – 7.3) kcal/mol = 4.5 kcal/mol (ans)
c) We are not sure what the energy change would mean; but in order to predict whether a reaction is favorable or not, we will assume that this indicates the free energy change. For a reaction to be favorable or spontaneous or not, the free energy change must be negative. Since Ecoupled is positive, the reaction in (a) is not favorable.