Explain the relationship between proteins and red blood cells. Make sure you discuss how structure can affect function.

Hemoglobin is a protein that carries oxygen in red blood cells. The structure is important to its oxygen carrying function: it has four protein chains and each chain has a ring-like group containing an iron atom. Oxygen binds reversibly to these iron atoms and is transported through blood. Any defect in the structure, such as in cases of sickle cell anemia, the carrying capacity of oxygen is reduced.

Protein is found to regulate blood cell size and number. Without proteins stability in red blood cells would be ... eh