Final answer:
Transferrin receptors on the surface of cells interact with the transferrin/iron complex and transport it into the cytoplasm.
Step-by-step explanation:
Transferrin receptors on the surface of cells interact with the transferrin/iron complex and transport it into the cytoplasm, where iron is then released. This process is known as receptor-mediated endocytosis.
Specific transferrin receptors on red blood cell surfaces bind the iron-transferrin molecules, and the cell endocytoses the receptor-ligand complexes.