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 chain attached to the heme portion of the molecule.
D) the number of oxygen molecules that can be carried.
E) the types of bone marrow that produce it.

Question

Quizplus · Accepted Answer

The difference between normal and sickle-cell hemoglobin is based on the substitution of one amino acid for another. In sickle-cell hemoglobin, valine is substituted for glutamic acid at the sixth position in the beta chain of the hemoglobin molecule. This single amino acid substitution causes the hemoglobin molecules to stick together, forming long, rod-like structures that distort the shape of red blood cells into a sickle shape.

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