Metals in Biology: Active Sites, Electron Transfer and Chelation · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

How proteins put metals to work

Science · Chemistry · ages 20-21
Name ______________________   Date ____________

  1. Where does oxygen bind in hemoglobin?

    • At the iron inside a heme ring
    • At a magnesium center
    • At the protein surface far from iron

  2. What is a ligand?

    • The metal at the center
    • A molecule or ion attached to a central metal
    • A free electron in solution

  3. Which metal does chlorophyll use to capture sunlight?

    • Lead
    • Iron
    • Magnesium

  4. Why can a chelator drug pull toxic lead from a patient?

    • It wraps the metal like a claw, forming an extra stable chelate
    • It changes lead atoms into iron atoms
    • It coats proteins so nothing binds at all

  5. When is a complex paramagnetic?

    • When all electrons pair up in the lower set
    • When no ligands surround the metal
    • When unpaired electrons remain after filling the split orbitals

  6. How does a protein tune a metal without changing the metal?

    • By heating the cell until orbitals merge
    • By choosing donor atoms and geometry, shifting orbital energies
    • By removing every ligand from the metal

  7. A chelator must remove toxic lead but spare useful iron. What argues it can?

    • Lead and iron have identical chemistry
    • All chelators bind every metal equally
    • Its stability constant favors lead over iron

  8. Two complexes with the same atoms always do the same job, since arrangement never matters.

    Circle one:   True   False

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Answer key

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

How proteins put metals to work W1-mt_gKhjhRXfMU-s1

  1. At the iron inside a heme ring · The iron held in the porphyrin ring is where oxygen attaches.
  2. A molecule or ion attached to a central metal · A ligand attaches to the metal by sharing an electron pair with it.
  3. Magnesium · Chlorophyll holds magnesium, tuned for catching light.
  4. It wraps the metal like a claw, forming an extra stable chelate · The claw grip holds lead tightly enough to carry it out safely.
  5. When unpaired electrons remain after filling the split orbitals · Unpaired electrons make the complex attracted to a magnet.
  6. By choosing donor atoms and geometry, shifting orbital energies · New surroundings shift the splitting, which moves the reduction potential.
  7. Its stability constant favors lead over iron · Selectivity is a stability constant argument, not luck.
  8. False · Isomers arrange the same atoms differently, which can change everything.
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