The difference between normal and sickle-cell hemoglobin is based upon
A) the number of amino acids in the molecule.
B) the substitution of one amino acid for another.
C) the number and orientation of the amino acid chains attached to the heme portion of the molecule.
D) the number of oxygen molecules that can be carried.
E) the type of bone marrow that produces it.

Question

Quizplus · Accepted Answer

The difference between normal and sickle-cell hemoglobin is based upon the substitution of one amino acid (glutamic acid) for another (valine) in the beta-chain of the hemoglobin molecule. This single amino acid change alters the shape of the hemoglobin molecule, leading to the characteristic sickling of red blood cells in individuals with sickle cell disease.

The Difference Between Normal and Sickle-Cell Hemoglobin Is Based Upon