Which components of the cell membrane control most material movements?

The embedded proteins in the cell membrane play a crucial role in controlling material movements across the membrane. These proteins function as channels, carriers, and receptors, enabling selective transport of substances into and out of the cell.

For example, channel proteins allow specific ions or molecules to pass through the membrane by creating a passageway, while carrier proteins can bind to substances and change shape to transport them. Additionally, receptor proteins are essential for receiving signals from the external environment, which can trigger further actions inside the cell, including the facilitation of certain materials crossing the membrane.

The lipid bilayer, primarily made up of phospholipids, provides a structural foundation for the membrane and contributes to its fluidity but does not directly engage in transport processes. Similarly, carbohydrates are often involved in cell recognition and signaling rather than in transport itself. Cholesterol serves to stabilize the membrane's structure and fluidity but does not directly control the movement of materials across the membrane.

Thus, the wide range of functionalities provided by embedded proteins emphasizes their vital role in regulating the movement of materials, making them the primary components responsible for this essential cellular process.