How does large changes in membrane potential caused by?
small change in ionic concentrations-the number of ions that need to move to generate a potential is very small -concentrations remain essentially constant
How to determine structure of K+ channel?
by X-ray crystallography-negatively charged amino acid around pore which attract positive ions
Process of K+ ion to enter selectivity filter .
K+ ion must lose all water molecules to enter -oxygen atoms in selectivity filter spaced perfectly to serve as replacement foroxygen atoms in water molecules stripped off
How does Na+ ion do in selectivity filter?
Na+ ion can not enter, even though it's smaller -oxygen atoms in selectivity filter too far away to compensate for energy loss of water molecules