Sickle cell anemia is a severe hereditary form of anemia in which a mutated form of hemoglobin distorts the red blood cells into a crescent shape at low oxygen levels. This disease is brought about by a single amino acid change from Glutamate (negatively charged) to Valine (nonpolar). Why do you think this crescent shape occurs? Glutamate’s interaction with the backbone of the protein structure allows for hydrogen bonds to hold the rounded shape of hemoglobin Since Valine is hydrophilic in nature, it will cause the hemoglobin protein structure to fold away from the polar water Since Glutamate is negatively charged; the positively charged center of the hemoglobin will repel it causing the rounded and not sickled shape Valine is a hydrophobic amino acid and is not attracted to the water solution, so it folds inward; unlike glutamate which is attracted to water