Question: how does the mutation that causes sickle cell anemia affect the hemoglobin molecule?
Answer: The mutation in the HBB gene in sickle cell anemia changes one of the amino acids, the building blocks of proteins, in the beta chain of hemoglobin. This defect causes the hemoglobin protein to stick together and form stiff fibers. These fibers distort the shape of the red blood cells and make them more fragile.