And that's because of these relatively weak non covalent interactions. So basically, these proteins and these phospholipids, the lipid molecules, can move along the membrane without any problem. So there's a constant state of motion among all these different molecules in the lateral direction on that cell membrane. So due to relatively weak intermolecular bonds, lipids and most proteins are in a constant state of lateral motion. The reason I say most proteins is because some of these proteins are actually attached to other things and so they don't actually move. Property number six, proteins diversify the properties of cell membranes.