(Solved): 1. The pathway shown here is part of the cholesterol biosynthetic pathway. The G value of one ...

1. The pathway shown here is part of the cholesterol biosynthetic pathway. The $?{\mathrm{G}}^{?}$ value of one of the three steps shown in the pathway can be positive in a normal, healthy cell. The three overall steps to consider are 1) the thiolase-catalyzed step, 2) the HMG-CoA synthase-catalyzed step, and 3) the HMGCoA reductase-catalyzed step. a. What does it mean for a reaction to have a positive $?{\mathrm{G}}^{?}$ value in the context of a metabolic pathway? b. Identify the step that could have a positive $?{\mathrm{G}}^{?}$ value and briefly justify your choice. Be sure to mention what would determine whether the step has a positive $?{\mathrm{G}}^{?}$ value. Note: Reaction coupling is not relevant to answering this question because the $?G^{?}$ value of the overall reaction will be negative. Be sure to notice what arrows communicate about the pathway.