Answer the following question given this paragraph: 

Figure 3.26 The beta chain of hemoglobin is 147 residues in length, yet a single amino acid substitution leads to sickle cell anemia. In normal hemoglobin, the amino acid at position seven is glutamate. In sickle cell hemoglobin, this glutamate is replaced by a valine.


Q: A single amino acid substitution in hemoglobin leads to what disease?


A:
sickle cell anemia