In heme synthesis in mammalian cells:

    1. Uroporphyrin III is the immediate precursor of coproporphyrin III
    2. d-aminolevulinic acid is formed by the condensation of succinyl CoA and valine
    3. Ferric iron is inserted into protoporphyrin IX prior to attachment to the globin molecule
    4. Porphobilinogen is formed by the condensation of two d-aminolevulinic acids
  1. A, B and C
  2. A and C
  3. B and D
  4. D only
  5. All of the above


    1. Neither compound is on the pathway of heme synthesis.
    2. Succinyl CoA condenses with glycine, not valine.
    3. It is iron (II), or ferrous iron, that is inserted.
    4. Correct. This is a dehydration reaction.

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