And the sugar protein combinations are known as glycoproteins. Glycoproteins are important because these sugar components can basically allow some outside type of molecule to bind onto our sugar component of that protein. And we'll talk more about this when we get into biochemistry of cell membranes. Now, the next aspect of the cell membrane that I'd like to discuss is a model known as the fluid mosaic model, which basically describes the way that our molecules down inside the cell membrane interact and move. So the question is, do our phospholipids and proteins remain stationary in place or are they in a constant fluidlike state of motion? So, to answer this question, we have to note the following important point.