So things like the nucleus, the Golgi complex, the endoplasm reticulum, lysosomes, paroxysomes, all these organelles also contain their own membrane that basically plays the same type of role as the cell membrane found around the actual cell. Now, property number two, cell membranes are made up of not only lipids, but also proteins and carbohydrates. And the additional proteins and carbohydrates basically diversify the functionality of that cell membrane. Now, depending on the type of cell and the activity of cell, the ratio of lipids to proteins to carbohydrates basically varies. Now property number three, the cell membrane consists of a phospholipid bilayer and that can be seen in the following diagram. Now, generally speaking, as we'll see in a future lecture, lipids are amphatic molecules and what that means is they contain both hydrophobic and hydrophilic regions, non polar and polar regions.