Final answer:
Protein structure is organized into primary, secondary, tertiary, and quaternary levels. Primary structure is the amino acid sequence, secondary structure is the folding or coiling of the protein, tertiary structure refers to the 3D arrangement, and quaternary structure involves protein subunit interactions.
Step-by-step explanation:
The structure of a protein can be described in four levels of organization: primary, secondary, tertiary, and quaternary structure. The primary structure refers to the sequence of amino acids in the protein's polypeptide chain. Secondary structure involves the folding or coiling of the protein chain into alpha helices or beta sheets. Tertiary structure refers to the three-dimensional arrangement of the protein's folded structure. Quaternary structure involves the interaction of multiple protein subunits to form a functional protein complex.