And function number two of lipids is to actually create a medium, an environment in which the proteins can actually dissolve in, because ultimately, it's the proteins that carry out nearly all the other functions of that particular membrane. So, remember, the proteins greatly diversify the functionality of cell membranes. They basically carry out processes such as signal transduction pathway, communication pathways. They actually move the molecules and particles across the cell membrane, and they also create an energy storage system, for instance, when they create proton gradients, that creates a separation of charge between the two sides of the membrane. And within that separation of charge, we store energy, electric potential energy. Now, depending on the type of membrane that we're examining, and depending on the functionality of that membrane, the mass ratio of lipids to proteins can basically differ.