The primary structure of a protein refers to

  • A. the sequence of amino acids joined by peptide bonds
  • B. the coiling of the chain into a helix
  • C. the folding of the chain into a globular shape
  • D. the association of several chains

Explanation

Primary structure is simply the order of the residues, and it determines every higher level of structure, because the chain folds according to the interactions between its own side chains. A single change in that sequence can be catastrophic, as one substitution in haemoglobin causes sickle cell anaemia. The peptide bonds of the primary structure survive denaturation.

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