For this type of question, you’re meant to match each picture of a protein to one of the four levels of protein structure, in order of increasing complexity: primary → secondary → tertiary → quaternary.

Here’s how to sort the images conceptually:

  1. Primary structure
    • Looks like: A simple linear chain or “string” of beads (amino acids in a sequence), no obvious 3D folding.
    • Put into the bin labeled “Primary structure.”
  2. Secondary structure
    • Looks like: Regular repeating shapes such as:
      • A spiral/coil (α-helix) or
      • A zig‑zag/flat arrow sheet (β‑pleated sheet).
    • Usually just a short segment, not a full globular protein.
    • Put into the bin labeled “Secondary structure.”
  1. Tertiary structure
    • Looks like: One single polypeptide chain fully folded into a complex 3D globular shape, often with helices and sheets packed together like a tangled ribbon ball.
    • Only one chain/subunit is present.
    • Put into the bin labeled “Tertiary structure.”
  1. Quaternary structure
    • Looks like: Two or more separate folded subunits stuck together, often drawn as several “globules” or “clews” joining into one larger complex.
    • Example description from many homework problems: “Two types of thick coiled threads form four clews, which together form a ball‑shaped structure” → this is quaternary.
    • Put into the bin labeled “Quaternary structure.”

If your question uses four images, the correct logical order from “least structured” to “most structured” is:

  • Primary → Secondary → Tertiary → Quaternary.

Since I cannot see your exact figures, match them using these visual cues:

  • “Simple chain” → primary
  • “Single helix or sheet” → secondary
  • “Single folded blob” → tertiary
  • “Multiple blobs together” → quaternary