Final answer:
The side chain, or R group, attached to the α-carbon of an amino acid is what imparts unique properties to each amino acid, affecting the structure and function of proteins they compose.
Step-by-step explanation:
The component of an amino acid that gives it unique properties is the side chain, often referred to as the R group. This variable group is attached to the α-carbon (alpha-carbon), differentiating one amino acid from another. The characteristics of the side chain, such as size, shape, solubility, and electrical charge, contribute significantly to the amino acid's properties and ultimately affect protein structure and function.
Each amino acid side chain can range from a simple hydrogen atom, as in glycine, to more complex structures with specific functional groups. These differences in the side chains are crucial because they determine how amino acids interact with each other and how a protein will fold, affecting its overall biological activity. Therefore, the correct choice that indicates which part of an amino acid gives it its unique properties is C. side chain.