Now when it comes to our membrane structure, we follow what's called a fluid mosaic model. Here, this is a model for representing the general structure of a cell membrane. Now, when we say the word fluid, we're going to say the lipid bilayer is not rigid but fluid and dynamic. We're going to say here, phospholipids in the lipid bilayer do not fit closely together due to kinks in the fatty acid chains. So here we have our phospholipid, and we're going to say that we have the polar heads orienting themselves on the externals, and then we have our hydrophobic tails on the interior of forming this lipid bilayer.
Now, Mosaic is basically the lipid bilayer also containing proteins, carbohydrates, and cholesterol molecules. If we take a look here, we're going to say that these two structures at the top represent our carbohydrate side chains. We have here, 4 fused rings together which means it's a steroid and specifically, it would be cholesterol. Next, we have here, this is called an integral protein. And if we're talking about integral proteins, we're going to say they extend through the entire bilayer and appear on both sides. We're going to say next, we have our peripheral proteins, They're associated with our with just one side. Our peripheral protein will be this green blob right here. It doesn't cut all the way through to over here like the integral proteins would.
We have our carbohydrate side chains that we talked about up top. These extend into the extracellular fluid, and they're responsible for cell recognition and communication. Now, we talked about these 4 fused rings here representing a steroid, but specifically cholesterol. So remember, cholesterol here resides within a bilayer and increases membrane strength based on how much cholesterol we have there. And then in terms of this, remember we talked about this being the polar heads, we have our non-polar tails, our hydrophobic tails in the inside, and then we have our polar heads over here. This would give us a good description of what we mean by a fluid mosaic model.