and a similar electrochemical potential (about 200 millivolts [mV] across the membrane) as modern cells have. Russell has long maintained that natural proton gradients played a central role in ...

The ability to maintain concentration gradients and sometimes move materials against them is vital to cell health and maintenance. Thanks to membrane barriers and transport proteins, the cell can ...

This difference, or "gradient," appears to be the basic structural ... in cell signaling and in regulating properties of the cell membrane but were not known to be spatially organized to regulate ...

This takes place when molecules diffuse across the cell membrane by travelling through specific transport proteins. It occurs down a concentration gradient - molecules move from an area of high to ...

and is one of the ways substances can move across the cell membrane, into or out of the cell. Products of digestion, dissolved in water, can pass across the wall of the small intestine by diffusion.

and the only gradients are transverse to the membrane. This is a one-dimensional reactor, and both the anode and cathode may be considered as stirred tank reactors (STR PEM fuel cell). Figure 2A.