3. The Protective “Sugar Coat”: The Glycocalyx
On the outer surface of the plasma membrane is a “cell coat” known as the glycocalyx. This layer consists of the polar carbohydrate chains attached to the membrane’s proteins and lipids. It also contains proteoglycans, which are specific carbohydrate chains bound to integral proteins. The glycocalyx serves several crucial roles for the cell.
- Protection: It helps shield the cell from physical and chemical injury by preventing direct contact with inappropriate substances.
- Recognition: It plays a key role in cell-cell recognition and interaction, allowing cells to identify each other and communicate properly.
- Attachment: It aids in attaching certain types of cells to components in the extracellular matrix, providing structural support.
After understanding the membrane’s structure and external features, we can now explore its most critical job: managing the flow of materials.