Question

match each level of protein structure organization to its definition. the final three - dimensional shape of a single polypeptide a three - dimensional shape formed from multiple polypeptides a shape formed when a polypeptide chain folds a chain of many amino acids linked by peptide bonds protein structure definition primary structure secondary structure tertiary structure quaternary structure

Explanation:

• Primary structure: It is the linear sequence of amino acids in a polypeptide chain, which is described by "a chain of many amino acids linked by peptide bonds".
• Secondary structure: It involves local folding of the polypeptide chain into structures like alpha - helices and beta - sheets. But in the given options, "a shape formed when a polypeptide chain folds" is more relevant as it starts the folding process conceptually (though secondary structure has more specific motifs).
• Tertiary structure: It is the final three - dimensional shape of a single polypeptide, resulting from further folding and interactions (e.g., hydrophobic interactions, disulfide bonds) of the secondary - structured polypeptide.
• Quaternary structure: It is formed when multiple polypeptides (sub - units) come together to form a multi - subunit complex, so it is described by "a three - dimensional shape formed from multiple polypeptides".

Answer:

• Primary structure: a chain of many amino acids linked by peptide bonds
• Secondary structure: a shape formed when a polypeptide chain folds
• Tertiary structure: the final three - dimensional shape of a single polypeptide
• Quaternary structure: a three - dimensional shape formed from multiple polypeptides