Normal red blood cells can easily travel through blood vessels, whereas sickle-shaped red blood cells get stuck. This is the basis of sickle cell anemia. What does this tell you about the relationship between the structure of a protein and its function in a cell/organism?

That's the protein in red blood cells that carries oxygen to the tissues of the body. So, sickle cell disease interferes with the delivery of oxygen to the tissues. Red blood cells with normal hemoglobin are smooth, disk-shaped, and flexible, like doughnuts without holes. They can move through the blood vessels easily.

So, due to change in the structure of protein, cells are not able to do their work properly. It means that protein structure is very important for its proper functioning and functioning of the cell.