[Campbell Biology P.131] What is the primary cause of sickle-cell disease, as described in t... | Practice Question

What is the primary cause of sickle-cell disease, as described in the text?

  • A: A substitution of glutamic acid for valine at the sixth amino acid position in hemoglobin.
  • B: A substitution of valine for glutamic acid at the sixth amino acid position in hemoglobin.
  • C: An addition of an extra amino acid to the hemoglobin primary structure.
  • D: A deletion of an amino acid from the hemoglobin primary structure.

Explanation

Sickle-cell disease is caused by a single amino acid substitution where valine replaces glutamic acid at the sixth position in the primary structure of hemoglobin. This seemingly minor change has profound effects on the protein's function and the shape of red blood cells.