The cell membrane is a double layer of lipid bilayers (lipid groups attached to the outside of the cells, and water molecules bound to the inside). The lipid bilayer is the main structural component of a cell membrane. It has many functions, such as protecting the cell from its surroundings and transporting substances in and out of the cell.
Functions of Cell Membrane
- Cell membranes are also involved in various other cellular processes including:
- Transport of materials across the membrane, such as nutrients and waste products. Some substances need to be transported by specific types of carrier proteins in order for them to be transported into or out of cells.
- Sorting out certain molecules based on their size, shape, charge or chemical properties. This allows for selective permeation (the passage) of specific molecules across the cell membrane. For example, some compounds only cross through specific pores in the membrane. The transport process depends on which type of transporter protein is present at each pore site.
- Protecting surfaces from damage by harmful substances that can leak into cells or harm their function if they do penetrate into cells (for example, toxins).
- Storing energy reserves within cells (such as sugars).