Question

. Hydrochloric acid is secreted into the stomach by parietal cells (also known as oxyntic cells) in the gastric lining. These cells contain a H+/K+ ATPase antiporter in their apical membrane. Gastric juice (pH 1.5) is produced by pumping HCl from blood plasma (pH 7.4) into the stomach. Calculate the amount of free energy required to concentrate the H+ in 1 L of gastric juice at 37 °C. Assume that [K+]outside = [K+]inside and that the net [K+] and [H+] remain constant both inside and outside the cell. Note that this is an electroneutral reaction, therefore the change in charge does not need to be calculated.