The substitution of valine for glutamine at the sixth position in the beta chain produces which type of hemoglobin?

The substitution of valine for glutamine at the sixth position in the beta chain is a hallmark of sickle cell hemoglobin, known as hemoglobin S (Hb-S). This mutation occurs in the gene that encodes the beta chain of hemoglobin, resulting in a structural change that affects the hemoglobin's properties. In Hb-S, the presence of valine creates a hydrophobic spot on the surface of the hemoglobin molecule, leading to the aggregation of hemoglobin molecules under low oxygen conditions. This aggregation causes red blood cells to deform into a sickle shape, which can obstruct blood flow and lead to various complications associated with sickle cell disease.

Other types of hemoglobin, like Hb-A, Hb-C, and Hb-F, have different structural compositions or functional characteristics, but they do not arise from this specific substitution of valine for glutamine at the sixth position in the beta chain. This makes Hb-S distinctly tied to the mutation described in the question.