Gastric juice is made up of substances secreted from parietal cells, chief cells
ID: 1061341 • Letter: G
Question
Gastric juice is made up of substances secreted from parietal cells, chief cells, and mucous-secreting cells. The cells secrete HCI, proteolytic enzyme zymogens, mucin, and intrinsic factor. The pH of gastric juice is acidic, between 1-3. If the pH of gastric juice is 2.1, what is the amount of energy (Delta G) required for the transport of hydrogen ions from a cell (internal pH of 7.4) into the stomach lumen? Assume that the potential difference across the membrane separating the cell and the interior of the stomach is -80.0 mV (inside of cells negative relative to the lumen of the stomach). Assume that the temperature is 37 degree C. The Faraday constant is 96.5 kJ middot V^-1 middot mol^-1 and the gas constant is 8.314 times 10^-3 kJ middot mol^-1 middot K^-1. Express your answer in kJ/mol.Explanation / Answer
We need
dG total = dG1 + dG2
dG1 = -RT*ln(C2/C1)
dG2 = Z*F*dY
so..
T = 37°C = 310 K
C2 = 10^-pH out
C1 = 10^-pH in
dG1 = -8.314*(310)*ln((10^-7.4)/(10^-2.1)) = 31453.086 J/mol
for
G2:
dG2 = -nF*E°cell = -1*(96.5*10^3)*(-80*10^-3) = 7720 J/mol
total dG
dG = 7720 + 31453.086
dG = 39173.086 J/mol = 39.17 kJ/mol
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