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Biomacromolecules

Identify the macromolecule category from its chemical structure

How to play the biomacromolecule puzzle

Each day you are shown a different biomacromolecule drawn as a 2D chemical structure.

  1. Study the structure and molecular formula. You can optionally click "Reveal molecule name" at no penalty.
  2. Round 1 (scored): Choose one of the four macromolecule categories: Carbohydrate, Lipid, Nucleic Acid, or Protein. A correct answer counts as a win and extends your streak; a wrong answer resets the streak.
  3. Round 2 (for fun): Identify the subcategory from four choices. This does not affect your score.
Carbohydrates (monosaccharides)
  • Should have about the same number of oxygens as carbons.
  • Look for hydroxyl groups (–OH) attached to the carbon atoms.
  • Carbonyl groups (C=O) are often present as well.
  • Look for the base unit of CH2O.
  • Larger carbohydrates will form hexagon or pentagon ring-like structures.
Lipids (fatty acids)
  • Contain mostly carbon and hydrogen.
  • Very few oxygens and often no nitrogens.
  • Fats and oils will have carboxyl groups (–COOH) and ester bonds.
  • Look for long chains or ring structures of only carbon and hydrogen.
  • Steroids have four interconnected carbon rings.
Proteins (amino acids and dipeptides)
  • Always have a nitrogen/amino group (–NH2 or –NH3+).
  • Always have a carboxyl group (–COOH or –COO–).
  • Identify the central Cα (alpha-carbon) attached to an amino group and a carboxyl group.
  • Larger protein macromolecules will have a characteristic peptide bond (C–N).
  • Try to identify common side chains (R groups).
Nucleic acids (nucleobases)
  • Must have a nucleobase, rings containing carbon and nitrogen.
  • Larger nucleic acids will have a sugar backbone and phosphate groups.
Phosphate groups (–PO42–)
  • Found in all of the macromolecule types.
  • It is best to ignore them so they don't confuse you.
  • The breakdown of carbohydrates involves adding phosphates.
  • Membrane lipids have phosphate head groups.
  • Many proteins are phosphorylated for regulatory purposes.
  • DNA has a phosphate backbone.