Glutamic acid (Glu) and valine (Val) are two amino acids with different molecular structures. (Glutamic acid is a strongly hydrophilic molecule, and valine is a strongly hydrophobic molecule). Why do you think switching the hemoglobin gene's sixth amino acid from glutamic acid to valine would affect the hemoglobin protein

Hemoglobin is the red color pigment that gives the red color to the blood. This pigment is responsible for the binding and transport of oxygen to the different parts of body.

The change in the amino acid from glutamic acid to the valine affects the protein structure and increases the hydrophobicity of the protein. This affects the protein folding and changes the function of the protein as protein are specific to their structures. The structure of the RBCs become sickle cell from the normal shape.