Question

Sickle-cell anemia results from a point mutation in the HBB gene. The mutation results in the replacement of an amino acid that has a hydrophilic R-group with an amino acid that has a hydrophobic R-group on the exterior of the hemoglobin protein. Such a mutation would most likely result in altered
a) properties of the molecule as a result of abnormal interactions between adjacent hemoglobin molecules
b) DNA structure as a result of abnormal hydrogen bonding between nitrogenous bases
c) fatty acid structure as a result of changes in ionic interactions between adjacent fatty acid chains
d) protein secondary structure as a result of abnormal hydrophobic interactions between R-groups in the backbone of the protein

Answer 1

Answer:

a) properties of the molecule as a result of abnormal interactions between adjacent hemoglobin molecules

Explanation:

In sickle cell disease, for example, a nonpolar amino acid (valine) replaces a polar amino acid (glutamate). This substitution of amino acids reduces the hemoglobin’s water solubility. The mutated hemoglobin molecules form long, stiff and rod-like crystals inside red blood cells which are otherwise not formed by normal hemoglobin molecules.

These abnormal crystals of hemoglobin cause the deformation of RBCs making them sickle-shaped that cannot properly squeeze through narrow blood vessels. Therefore, the substitution of single amino acid results in abnormal interaction of two or more hemoglobin molecules that are not exhibited by normal hemoglobin molecules.