How do ion channels transport only specific ions?

Question

Ion channels, such as $Na^+$ channels and $K^+$ channels, are higly specific for ion permeability. But how do these channels achieve and maintain this specificity? Like how does a $K^+$ channel transport only $K^+$ ions (same for other channels like $Na^+$, $Ca^{2+}$, $Cl^-$, etc. channel)?

Answer 1

Hello. Aren't molecules cool? The basic answer to your question is that each channel is specifically formed and shaped to react to only one particular size or specific electronegativity of a particular atom. Remember that ion channels are working on the anatomical level and can detect the size and overall charge difference of individual atoms with the same sensitivity that you or I would be able to detect the difference in size or color of separate species of flowers or seeds. Please let me know if you have any further questions.