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

Since the mutation affects an amino acid, we know that the protein structure would be modified. The question is not related to DNA structures or fatty acid structures.

Protein secondary structure occurs mainly through hydrogen bonding between the carboxyl and amine groups in the chain, rather than the R group.

The question implies that the mutation affects an amino acid on the exterior of the hemoglobin molecule, hinting that the molecule would likely have altered interactions between nearby molecules.