Protein Structure from Primary to Quaternary · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Four levels from chain to working machine

Science · Organisms & Life Processes · ages 16-18
Name ______________________   Date ____________

  1. Which bonds hold the secondary structure of helices and sheets?

    • Peptide bonds between side chains
    • Hydrogen bonds between backbone parts
    • Sulfur bridges between separate chains

  2. Which bonds hold the primary structure of a protein?

    • Peptide bonds between amino acids
    • Hydrogen bonds between backbone parts
    • Ionic attractions between folded chains

  3. Quaternary structure packs several folded chains together.

    Circle one:   True   False

  4. A protein is gently heated. Which bonds break first?

    • The hydrogen bonds and ionic grips
    • The tough peptide bonds of the order
    • Every bond at exactly the same moment

  5. Why does one swapped amino acid cause sickle cell disease?

    • It deletes the whole haemoglobin chain
    • It adds an extra chain to every protein
    • The fold shifts so fibres clump

  6. Where do water fearing side chains end up during folding?

    • Spread evenly across the surface
    • Buried inward, away from water
    • Broken off and discarded

  7. A student says quaternary structure means one chain folded four times. What is wrong?

    • Chains cannot fold at all
    • Only two levels of structure exist
    • Several folded chains together

  8. Boiling an egg breaks its peptide bonds, which is why it cannot uncook.

    Circle one:   True   False

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Answer key

For grown-ups. Fold this page away before handing over the rest.

Four levels from chain to working machine W1-mt_bMdQS2lqSI-s1

  1. Hydrogen bonds between backbone parts · Backbone hydrogen bonds coil and fold the chain into helices and sheets.
  2. Peptide bonds between amino acids · The bare order of amino acids is pinned by tough peptide bonds.
  3. True · The fourth level is chains packed together, not one chain folded again.
  4. The hydrogen bonds and ionic grips · Heat shakes weak folds apart while the peptide chain survives.
  5. The fold shifts so fibres clump · Order decides fold and fold decides job, so one swap rebuilds the ending.
  6. Buried inward, away from water · Hiding inward shelters them, while charged pieces take the surface.
  7. Several folded chains together · Four levels count kinds of organisation, and the top one gathers chains.
  8. False · Heat wrecks the folds while the peptide order survives, and cooling cannot rebuild the shape.
Worksheet · LightMySky