Biology I / What Is Life? The Chemistry of Living Things
Practice question · Match the pairs

Match each level of protein structure to what holds it together.

  • Primary structure
  • Secondary structure
  • Tertiary structure
  • Quaternary structure
  • Side-chain interactions folding the whole chain
  • Hydrogen bonds forming helices and sheets
  • Association of several separate chains
  • Peptide bonds in a fixed sequence
Hints
  1. Each level is held by a different kind of interaction.
  2. Only the first level involves covalent bonds along the backbone.
Show the answer
  • Primary structure Peptide bonds in a fixed sequence
  • Secondary structure Hydrogen bonds forming helices and sheets
  • Tertiary structure Side-chain interactions folding the whole chain
  • Quaternary structure Association of several separate chains
Why

Only the primary level is covalent along the backbone; the higher levels are held by weaker interactions, which is exactly why heat or pH can destroy the fold while leaving the sequence intact.

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