Flipflop

When flip-flop is called in cell biology the " page break " of a lipid molecule in a cell membrane.

Biomembranes are composed of two lipid layers, wherein the water-repellant structures of molecules ( "tails" ) facing inward, the hydrophilic ( "heads" ) outwardly to the surface of the membrane ( ' inside ' and ' outside ' with respect to the membrane - comparable to a wall. ' external ' = surfaces ' internal ' = membrane body ).

The two levels of biological membranes behave as two-dimensional liquids. Although the lipid molecules can diffuse very freely within the membrane of its own plane, but only very difficult to leave this plane. A change from one side of the bilayer to the other is extremely unlikely and happens in a normal cell spontaneously only about once a minute. Thus there is in the cell membrane "inside" and "outside " in relation to the cell ( again the example ' wall ' between two rooms, one side is papered, the other tiled, wallpaper and tiles each remain on their side ).

A flip-flop can also be catalyzed by an enzyme called flippase. In this way, the cell can, inter alia, their topology, ie the curvature of the membrane actively define. It is also possible that the installation of new lipids initially unevenly happened, but later flip-flops restore the balance.

• Cell Biology
• Biological process