Carrier proteins are specialized proteins found in cell membranes that help transport substances across the membrane. They bind to specific molecules, such as ions or nutrients, and change shape to move these substances from one side of the membrane to the other. This process is essential for maintaining the proper balance of materials inside and outside of cells. These proteins play a crucial role in various biological processes, including cellular respiration and nutrient absorption. By facilitating the movement of molecules like glucose and amino acids, carrier proteins ensure that cells receive the necessary components for energy production and growth.