1. Calculate the free energy change for glucose entry into cells when the extrac
ID: 886977 • Letter: 1
Question
1. Calculate the free energy change for glucose entry into cells when the extracellular concentration is 4.2 mM and the intracellular concentration is 4.3 mM at 37oC. Express your answer in kJ/mol.
2. Calculate the free energy required to move 1 mol of K+ ions from the outside of the cell (where [K+] = 4.4 mM) to the inside (where [K+] = 137 mM) when the membrane potential is -71 mV and the temperature is 37.4°C. Give your answer in kJ/mol.
3. Calculate the chemical potential difference when intracellular [Na+] = 8.8 mM and extracellular [Na+] = 144 mM at 36.2°C. Give your answer in kJ/mol.
Explanation / Answer
1. DG = 2.303RTlog[glucose]i / [glucose]0
Glucose intra = 4.3 mM , Glucose extra = 4.2 mM
T = 37 C = 310 K. R = 8.314 j.k-.mol-1.
= 2.303*8.413*310log(4.3/4.2)
= 61.38 joule/mol
= 0.6138 kj/mol
2. DG = 2.303RTlog[K+i/[k+]0 + ZEF
z = 1 , E = potential = -71 mv , F = 96500 c
K+ intra = 137 mM , K+ outside = 4.4 mM
DG = 2.303*8.314*310.4*log(137/4.4) + 1*96500*(-71*10^(-3))
= 2.02 kj/mol
3. let us consider equilibrium state,free enrgy change DG = 0
DG = 2.303RTlog[K+i/[k+]0 + ZEF
0 = (2.303*8.314*319.2*log(8.8/144)) + (1*96500*(E))
E = 0.0768 V
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