What role do proteins play in the fluid mosaic model?

Proteins in the fluid mosaic model of cell membranes play a crucial role in facilitating the transport of molecules across the membrane. They serve as channels, allowing specific substances to pass through the lipid bilayer, which is otherwise impermeable to many polar and larger molecules. This transport is essential for maintaining cellular homeostasis, as it regulates the intake of nutrients and the removal of waste products.

The fluid mosaic model highlights the dynamic and flexible nature of the membrane, where various proteins are interspersed among phospholipids. These proteins may function as channels, carriers, or receptors, each contributing to the membrane's overall functionality. Channels can be specific to certain ions or molecules, ensuring that the cell can control its internal environment efficiently.

The other options describe functions that do not align with the primary roles of proteins in the fluid mosaic model. Structural support is typically provided by the phospholipid bilayer itself and other structural components. DNA replication is a function performed by enzymes, not proteins associated with the membrane. Energy storage is primarily the role of carbohydrates and lipids within the cell, rather than membrane proteins.