kthomson9 Posted April 24, 2010 Share Posted April 24, 2010 How many moles of ATP are required to pump one mole of Ca2+ out of a cell when the cytoplasmic concentration is 0.2 uM, the extracellular concentration is 1.8 mM, and the membrane potential is -55 mV? I know I have to use deltaG= RTln([Ain]/[Aout]) + ZFdeltaPsi but how do I get the number of moles of ATP from deltaG?? Link to comment Share on other sites More sharing options...
timo Posted April 24, 2010 Share Posted April 24, 2010 Perhaps you can just assume that one mole of ATP delivers that-much energy and that additional thermodynamical contributions of the ATP (say pressure or entropy of unused vs. used) can be neglected. That's just a blind guess of mine, though. I am, sadly, not familiar with the physics of transport through a membrane. Link to comment Share on other sites More sharing options...
Greippi Posted April 24, 2010 Share Posted April 24, 2010 Are you told anything about the mechanisms of transporting the Ca2+? maybe the active transporter uses a certain amount of ATP when pumping across the membrane? Link to comment Share on other sites More sharing options...
kthomson9 Posted April 25, 2010 Author Share Posted April 25, 2010 I solved the above equation and got deltaG= -10052.4 J I know that hydrolysis of 1 mol ATP releases -30543.2 J Would it make sense to just divide the energy needed (deltaG) by the amount of energy that 1 mol ATP provides?? I get a fraction of a mol of ATP though... Link to comment Share on other sites More sharing options...
Greippi Posted April 26, 2010 Share Posted April 26, 2010 That sounds reasonable to me. An entire mole of ATP would be a hell of a lot of ATP so I'm not surprised it's only a fraction of a mole. Link to comment Share on other sites More sharing options...
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