Question

2. For the following reaction: ATP+ creatine + H2O creatine phosphate + ADP + P, The relevant half reactions are: ATP → ADP + Pi Creatine phosphate + H2O-> creatine AG-30.5 kJ/mol ΔG°,--43.1 kJ/mol a. (2 pts.) Calculate the ΔG°, for the overall reaction. b. (2 pts.) Is the reaction spontaneous or non-spontaneous? Endergonic or exergonic?

Answer 1

Amount of usable energy (energy that can do work) in a system is Gibbs free energy. The spontaneity of a reaction can be measured using change in Gibbs free energy.

a. Change in Gibbs free energy or ∆G can be calculated as:
ΔG=∆G forward–∆G reverse

In the reaction ATP + Creatine + water - creatine phosphate + ADP+ pi

∆G reverse= - 43.1kj/ mole

∆G forward= - 30.5 kj/ mole

∆G = -30.5-(-43.1)= 12.6kj/ mole

b. Since ∆G is positive means the reaction is nonspontaneous and endergonic.