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Title: Spontaneus Post by: gh1991 on Sep 17, 2010 the cells of your body have Na+-K+-ATPases,
which use energy from ATP to pump Na+ out of the cell and K+ into the cell. One result of this is that there is an electrochemical gradient of Na+ ions across the plasma membrane, with more Na+ outside than inside the cell. -->given this gradient, in which direction will Na+ ions move spontaneously? -->if they would move spontaneously in one direction, why don’t they quickly come to equilibrium, with roughly equal concentration on each side of the plasma membrane? PLEASSEE HELP Title: Re: Spontaneus Post by: sarah! on Sep 17, 2010 Thanks for joining gh1991.
Q1 Sodium will have a tendency to move inside the cell. Q2 Depends on the permeability of the membrane. Moreover, for every three sodiums that move out, 2 potassium ions move in, so it is impossible to accomplish equilibrium. You are using active transport which requires energy, in the form of ATP, to go against the concentration gradient. Check out the following links for more clarification. http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120068/bio03.swf::Sodium-Potassium%20Exchange%20Pump (http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120068/bio03.swf::Sodium-Potassium%20Exchange%20Pump) http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120107/bio_a.swf::Sodium-Potassium%20Exchange (http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120107/bio_a.swf::Sodium-Potassium%20Exchange) |