Solution:
The physical organization and function of all plasma membranes depend on their constituents. These constituents are lipids, proteins, and carbohydrates.
Lipids establish the physical integrity of the membrane and, being hydrophobic substances, create an effective barrier for the rapid passage of hydrophilic materials such as water and ions.
On the other hand, a variety of proteins are embedded in the phospholipid bilayer. This general design is known as a fluid mosaic model.
The cell membrane is primarily made up of Phospholipids, Cholesterol, glycolipids, and Proteins.
Now, the types of proteins involved in this fluid mosaic model are:
1. Integral membrane proteins: have hydrophobic regions and penetrate the phospholipid bilayer.
2. Peripheral membrane proteins: s lack hydrophobic regions and are not embedded in the bilayer. Instead, they have polar or charged regions that interact with similar regions on exposed parts of integral membrane proteins or phospholipid molecules.
On the other hand, the three main types of lipids in cell membranes are phospholipids (the most abundant), cholesterol, and glycolipids.
All three types of lipids are amphipathic. This means that these lipids have hydrophilic and hydrophobic ends. This feature is very important. For example, when cell membranes are formed, phospholipids are assembled into two layers due to these hydrophilic and hydrophobic properties. In effect, the phosphate heads in each layer face the aqueous environment on either side, and the tails hide from the water between the layers of heads because they are hydrophobic.
On the other hand, we have that the cholesterol helps to regulate the molecules that enter and leave the cell because it holds the phospholipids together so they don't separate too much.
Finally, the glycolipids act in cell recognition and as antigen receptors