In heme synthesis in mammalian cells:

1. Succinyl CoA and alanine are the immediate substrates for formation of d-aminolevulinic acid
2. Ferric iron is inserted into protoporphyrin IX
3. Coproporphyrin IV is an intermediate
4. Porphobilinogen is formed by the condensation of two molecules of d-aminolevulinic acid

Right

1. The amino acid is glycine, not alanine
2. Ferrous iron, or iron (II), is inserted to make heme
3. Only the I and III series of porphyrins occur naturally
4. Correct, and the name of the enzyme is ALA dehydratase

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