Paper 2 · Proteins and Amino Acids
The primary structure of a protein is
Athe number and sequence of amino acids in its polypeptide chain
Bthe folding of its polypeptide chain into a compact three dimensional shape
Cthe association of two or more polypeptide chains into one functional molecule
Dthe coiling of its polypeptide chain into an alpha helix or beta pleated sheet
Explanation: Primary structure is nothing more than the order in which amino acids are joined by peptide bonds along one chain. Coiling into a helix or pleated sheet is secondary structure, folding into a compact shape is tertiary, and joining several chains into one molecule is quaternary.
Derived from ZIMSEC Biology Paper 2, Nov 2004, Q1