What characterizes the primary structure of proteins?

The primary structure of proteins is defined by the specific sequence of amino acids linked together by peptide bonds. This sequence is crucial because it determines the unique properties and function of the protein. Each amino acid in the chain contributes to the overall characteristics of the protein through its individual side chain or R-group.

The linear sequence of amino acids dictates how the protein will fold and form higher-level structures, such as secondary, tertiary, and quaternary structures. While factors such as folding patterns (like alpha-helices and beta-sheets), interactions between side chains, and overall three-dimensional shape are essential components of a protein's structure and function, they are considered aspects of secondary, tertiary, and quaternary structures. The primary structure is solely about the sequence of amino acids and their connections through peptide bonds, making it foundational to understanding protein biology.