Question

3. (a) S>P AG8.5 kcal/mol (b) S → P ΔG + 3.5 kcal/mol (c) S-P AG-3.5 kcal/mol (d) S-) P ΔG_-9.5 kcal/mol (e) S → P ΔG= +3.0 kcal/mol (f) S-) P ΔG__ 2.5 kcal/mol A. (5 points) Which reactions are spontaneous? B. Which reactions are not spontaneous? C. Which reaction(s) can "force" reaction (a) to proceed? D. Which reaction(s) can "force" reaction (e) to proceed? E. Which reaction can "force" both reaction (0) and (e) to proceed togethers at of a biochemical pathway?

Answer 1

A. The reactions having $\Delta$G negative are spontaneous. The steps (c), (d), and (f) having  $\Delta$G negative value are spontaneous because the reactions have sufficient free energy to proceed spontaneously.

B. The reactions having  $\Delta$G positive value are not spontaneous because they require energy to proceed spontaneously. The reactions (a, (b), and (e) have positive  $\Delta$G, so they are not spontaneous.

C. Reaction (a) have  $\Delta$G = + 8.5 kcal/mol, so we need its  $\Delta$G negative to make it spontaneous, in order to do that we can choose a rection having  $\Delta$G greater negative than +8.5kcal/mol. From the above reactions only rection (d) has  $\Delta$G = -9.5 kcal/mol. Therefore, this rection can make reaction to proceed spontaneously. Overall  $\Delta$G= 8.5 -9.5 =-1 kcal/mol.

D. Reaction (c) and (d), having greater  $\Delta$G than reaction (e), can force the reaction (e) to proceed spontaneously.

E. Reaction (d) can force both reaction (b) and (e) to proceed together as a part of the biochemical pathway.