What is the primary structure of a protein?

The primary structure of a protein is defined as the specific sequence of amino acids in the polypeptide chain. This sequence is crucial because it determines how the protein will fold and function. Each amino acid is linked to its neighbor in a chain via peptide bonds, and the unique order of these amino acids encodes the information necessary for subsequent levels of protein structure (secondary, tertiary, and quaternary), which are influenced by the properties of the individual amino acids.

This sequence is fundamental because even a single amino acid replacement can lead to significant changes in a protein's properties and functions, which can impact biological processes. This term refers specifically to the linear arrangement of amino acids, without considering how they interact or fold upon themselves, which is reserved for higher levels of protein structure.