In heme synthesis in mammalian cells:

A. Uroporphyrin III is the immediate precursor of
coproporphyrin III
B. d-aminolevulinic acid is formed by the condensation of
succinyl CoA and valine
C. Ferric iron is inserted into protoporphyrin IX
prior to attachment to the globin molecule
D. 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

Right!

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

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