Ion Channels the Nanotransistors of Biology

The smallest forms of life are bacteria, which are single cells of micrometer size. Cells are enclosed by an impermeable lipid bilayer membrane, the cell wall. This hydrophobic layer is akin to a soap bubble. Lipid cell walls are ubiquitous in all forms of life. Communication from the cell to the extracellular environment is accomplished in part by ion channels, which allow specific ion species to enter or leave the cell.

Two specific types of transmembrane protein ion channels are the Ca++ gated potassium channel, and the voltage-gated potassium ion channel, which is essential to the generation of nerve impulses. The dimensions of these transmembrane proteins are on the same order as their close relatives, the rotary engines, which were characterized as 8 nm in diameter and 14 nm in length.

These ion channel structures are "highly conserved", meaning that the essential units which appeared about 1 billion years ago in single cells, have been elaborated upon, but not essentially changed, in the many different cellular applications that have since evolved.

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