Question

In dog skeletal muscle, the extracellular and intracellular concentration of Na+ are 150 mM and 12 mM, and those of K+ are 2.7 mM and 140 mM, respectively. Calculate the total free energy change as 3 Na+ are transported out and 2 K+ are transported in by the Na+-K+ pump. Assume that the temperature is 25°C and the membrane potential is –60 mV. Give your answer in kJ/mol to 1 decimal place.

Answer 1

a: Calculate the energy required to transport 3 Na+ outside the cell, and that required to transport 2 K+ inside the cell separately as shown below-

Given- [Na ], Ex Cell Na moves from (reactant/origin site) cell to (product/destination site) blood plasma. [Na ], in cell 15

[K ], Ex cell Given- [K*], in Cell 140 mM 2.7 mM Na moves from (reactant/origin site) cell to (product/destination site) blood

# Now, total energy required to simultaneously transport 3 Na+ out and 2K+ inside the cell = energy required for (3Na+ transport + 2 K+ transport)

= 36.15 kJ mol-1 + 8.00 kJ mol-1 = 44.00 kJ mol-1

b: Enthalpy of ATP hydrolysis = -30.5 kJ mol-1

That is, Energy released from hydrolysis of 1 mol ATP = 30.5

Conclusion: Since the energy released from hydrolysis of 1 mol ATP is LESSER than that of the energy required for simultaneous transport of (3Na+ transport + 2 K+ transport), the hydrolysis of a single mol ATP is NOT sufficient to drive the Na+-K+ pump under given conditions.

Answer 2

the total free energy change as 3 Na+ are transported out and 2 K+ are transported in by the Na+-K+ pump = 44.18KJ

Step-by-step explanation:

check for the explanation in the attachment below.