Question 1 of 13
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In heme synthesis in mammalian cells:
- A. succinyl CoA and alanine are the immediate substrates for
formation of delta-aminolevulinic acid.
- B. ferric iron is inserted into protoporphyrin IX.
- C. coproporphyrin IV is an intermediate.
- D. porphobilinogen is formed by the condensation of two
molecules of delta-aminolevulinic acid.
The correct answer is (D).
Comments:
- A. The amino acid is glycine, not alanine.
- B. Ferrous iron, or iron (II), is inserted to make heme.
- C. Only the I and III series of porphyrins occur naturally.
- D. Correct, and the name of the enzyme is ALA dehydratase.
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Last modified 1/5/95