In the situations described below, what is the free energy change if 1 mole of Na+ is transported across a membrane from a region where the concentration is 1 μM to a region where it is 100 μM? (Assume T = 37 oC.)
a. In the absence of a membrane potential.
b. When the transport is opposed by a membrane potential of 70 mV.
c. In each case, will hydrolysis of 1 mole of ATP suffice to drive the trans-port of 1 mole of ion, assuming pH 7.4 and the following cytoplamic concentrations: ATP = 4.60 mM, Pi = 5.10 mM, ADP = 310 μM?