84.

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Page 18

		1.2.4— The Currents Through Ion Channels Are Self-Similar in Time

		Ion channels are proteins in the cell membrane with a central hole that allows ions such as sodium, potassium, and chloride to get into or out of the cell. The structure of the ion channel protein can change, closing this hole and blocking the flow of ions. The small electrical current (10-12 amp) due to these ions can be measured in an individual ion channel molecule. This current is high when the channel is open and low when it is closed.

		When a recording of current is played back at low time resolution, the times during which the channel was open and closed can be seen. When one of these open or closed times is played back at higher time resolution, it can be seen to consist of many briefer open and closed times.

		The current through the channel is self-similar in time because the pattern of open and closed times found at low time resolution is repeated in the open and closed times found at higher time resolution.

 

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