The image presented in the next page is an representation of

The image presented in the next page is an representation of a potassium protein channel found in animal cells. The protein is colored blue and the potassium ion located in the center is colored purple; some oxygen atoms have been colored in red and these cover the space the potassium ion must travel through. Can you explain how is it possible for this channel to permit the exclusive passage of potassium ions but no other metallic or nonmetallic element? 1.

Solution

The potassium channel has two parts the filter and the gating domain. The filter selects the potassium ion while the gating domain regulate the flow of potassium through the channel i.e,opening and closing of channel. This gating domain will response to partiuclar stimuli and will open the domain.

In general the potassium ions are sorrounded by water molecules. To pass through the channel pore the potassium ion has to leave water molecules as the channel filters as desinged to mimic water molecules by protein oxygen atoms (as shown red in the picture above).The filters are selective here other ions like sodium are slightly smaller in size and cant interact with oxygen atom present in the pores, so sodium ions are stable when sorrounded by water molecules than with the oxygen atoms present in the channel, so the sodium ion cant enter the channel. when the potassium ion pass through the channel again it is sorrounded by water molecule.