What are the components of the cell membrane?
Basically, the cell membrane is composed of a phospholipid bilayer. Phospholipids are building blocks consisting of a water-loving, i.e. hydrophilic, head and a tail formed by 2 fatty acids. The part consisting of fatty acids is hydrophobic, which means that it repels water.
In the bilayer of phospholipids, the hydrophobic parts point towards each other. The hydrophilic parts point to the outside and inside of the cell. Due to this structure of the membrane, 2 aqueous environments can be separated from each other.
Furthermore, the cell membrane contains sphingolipids and cholesterol. These substances regulate the structure and fluidity of the cell membrane. The fluidity is a measure of how well proteins can move in the cell membrane.
The higher the fluidity of a cell membrane, the more easily proteins can move within it. In addition, there are many different proteins in the cell membrane. These proteins serve to transport substances through the membrane or interact with the environment.
This interaction can be achieved by direct binding between neighboring cells or by messenger substances that bind to the membrane proteins. The following topic might also be interesting for you: Cell plasma in the human bodyPhospholipids are the main component of the cell membrane. Phospholipids are amphiphilic.
This means that they consist of a hydrophilic and a hydrophobic part. This property of phospholipids enables the cell interior to be separated from the environment. There are different forms of phospholipids.
The hydrophilic backbone of the phospholipids consists of either glycerol or sphingosine. Both forms have in common that two hydrophobic hydrocarbon chains are attached to the basic structure. Cholesterol is contained in the cell membrane to regulate fluidity.
A constant fluidity is very important to maintain the transport processes of the cell membrane. At high temperatures the cell membrane tends to become fluid. The bonds between phospholipids, which are already weak under normal circumstances, are even weaker at high temperatures.
Due to its rigid structure, cholesterol contributes to maintaining a certain strength. The situation is different at low temperatures. Here the membrane can become too solid.
Phospholipids, which have saturated fatty acids as hydrophobic components, become particularly solid. This means that the phospholipids can be very close together. In this case, cholesterol stored in the cell membrane causes increased fluidity, since cholesterol contains a rigid ring structure and thus acts as a spacer. You can find detailed information on the topic of “cholesterol” at
- LDL – “low density lipoprotein
- HDL – “high density lipoprotein
- Cholesterol esterase – It is important for this
