Hemoglobin is a protein used by humans to carry oxygen in the blood. It is composed of four polypeptide subunits (two alpha and two beta subunits).
Sickle cell anemia is a disease caused by a genetic mutation that results in the amino acid valine being incorporated instead of glutamic acid at a particular position in the polypeptide chain of the beta subunits.
The consequence is that the hemoglobin proteins in people suffering from sickle cell anemia fold in such a way that their ability to carry oxygen is drastically reduced.
Based on this information, one can conclude that sick-cell hemoglobin proteins display