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

Question

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

Accepted Answer

The difference between normal and sickle-cell hemoglobin is based on the substitution of one amino acid for another. Normal hemoglobin has glutamic acid at the sixth position of the beta chain, while sickle-cell hemoglobin has valine instead. This single amino acid substitution causes sickle-cell hemoglobin to form abnormal hemoglobin molecules that can deform red blood cells into a sickle shape, leading to various health problems.