🚀 go-pugleaf

bhoughto@cmdnfs.intel.com (Blair P. Houghton) writes:
>In article <1990Nov6.235518.8507@alchemy.chem.utoronto.ca> mroussel@alchemy.chem.utoronto.ca (Marc Roussel) writes:
>>     This is certainly true.  You are both focussing on the wrong aspect of
>>the problem however.  It is not the size of the molecules that matters,
>>but their area of contact with the membrane.

>If the contact plugs a hole then it plugs traffic in both directions.

I'm not sure I agree.  This would be true if the molecule plugs the
hole for some length of time, but not if a point on the molecule just
bounces off of the membrane.

Say that when a water molecule hits the membrane, it has a certain
probability of passing through.  If it approaches from the opposite
side as the other molecule and gets there just before the other molecule
bounces, it will be able to pass through the membrane before striking
the other molecule.  Similarly, if it gets there just after the bounce,
it will be able get through.  Water molecules on the same side of the
membrane as the other molecule, on the other hand, will be excuded from
that neighborhood of the membrane for a short time.  Put another way,
the pressure of the water on one side will be able to push the plug
out of the way, but the water on the same side as the plug will be
blocked.

Richard M. Mathews			D efend
Locus Computing Corporation		 E stonian-Latvian-Lithuanian
richard@locus.com			  I ndependence
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