If a membrane is semi-permeable to lets say K+, and K+ is dissolved in 2 separate sides of this semi permeable membrane, why does K+ diffuse from higher concentration to lower concentration? What drives the movement?
2006-11-15 15:57:56 · 4 answers · asked by Brian B 4 in Science & Mathematics ➔ Biology
Ok, forget about charge, what if it were uncharged, glucose for example? Why would glucose move down its concentration gradient. I'm not asking for formulas, just an explanation as to why this happens.
2006-11-15 16:09:47 · update #1
Why would collisions make a particle diffuse through a pore though?
2006-11-15 16:12:32 · update #2
At any time, the number of molecules colliding with the membrane is proportional to its concentration. Since the membrane is permeable to your molecule, the number of molecules passing from concentrated side to diluted side is more than vice-versa.This gives the appearance of molecules moving down the concentration gradient. Just remember that the process occurs on both sides but is higher on concentrated side. When concentrations get equal, the molecules going to either side is equal and there is no net change. Dont you wonder why this stage is called equilibrium?
2006-11-16 03:24:04 · answer #1 · answered by Defunct 2 · 0⤊ 0⤋
When the concentrations are different, theres electric potential across the membrane. In a very basic way, that's the force that drives it. Let me know if you need me to go in more detail, becuase there's a few formulas that I don't feel like typing out.
Admittedly, it is a difficult thing to visualize. The molecules obviously don't "know" what's on the other side of the membrane, so why do they cross over? Basically, nature tends towards balance and eliminates potential energy wherever it can. What you have to realize about this membrane is that molecules are always moving and randomly crossing it all the time, regardless of concentrations. The ideal "balance" is for water to surround and interact with each molecle, surrounding it in a really loose crystalline way. The molecules will randomly shift across the membrane until the concentration is uniform.
2006-11-15 16:05:56 · answer #2 · answered by rowdyowl 2 · 0⤊ 0⤋
If we can visualize this, the tendency of the nature world and its movement towards empty space. The theory is based on pressure gradients and vacuum creation like Black holes etc.
2006-11-15 17:57:32 · answer #3 · answered by earth_spirit2004 1 · 0⤊ 0⤋
I think because when the K+ atoms run into each other they push each other apart.
2006-11-15 16:07:49 · answer #4 · answered by john_h_dawson 1 · 0⤊ 0⤋