Lipids and the Passive Cell Membrane

Lipids are water insoluble, oily, or greasy organic substances. They are the most important storage forms of chemical energy in the body. In our context, one group of lipids is of 

Even if the conductivity of the BLM itself is very low, the membrane is so thin that the capacitance is very high and die breakdown potential low. The electric field strength with a potential difference of 70 mV and a thickness of 7 nm is 10 kV/mm. This represents a large dielectric strength, but not larger than, for example. Teflon . In addition, as we shall see, this is not the potential across the bilayer itself but the potential of the bilayer plus the 

Some of the carbohydrates are receptor substances binding substances such as hormones, and some are important for the immunological properties of a cell. 

An electric double layer covers die wetted outer cell membrane surface. The total cell has a net charge revealed by its electrophoretic mobility. The cell membrane capacitance with the thickness of approximately 7 nm is on the order of 1 pF/cm. The frequency dependence of the membrane capacitance has been a subject of dispute (Cole, 1972), but the BLM as such is often considered to have a frequency-independent membrane capacitance. 

When the potential difference is increased more than 150 mV, the membrane breaks down (cf, Section 10.11.1) on electroporation. This must not be confused with the excitation process, in which the ionic channels of the membrane suddenly open (cf. Chapter 5). 

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