Final answer:
Carrier proteins are transport proteins that bind with specific ions or molecules and move them across the cell membrane by changing shape.
Step-by-step explanation:
Carrier proteins are transport proteins that bind with specific ions or molecules and move them across the cell membrane by changing shape. These proteins are specific for a single solute or a closely related family of solutes. For example, the GLUT1 carrier protein facilitates the transport of glucose across cell membranes. Carrier proteins are involved in both passive and active transport, depending on the concentration gradient and energy requirement.