Question 10 of 13

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In heme synthesis in mammalian cells:

1. uroporphyrin III is the immediate precursor of coproporhyrin III.
2. delta-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 delta- amino-levulinic acids.

A. 1, 2 and 3

B. 1 and 3

C. 2 and 4

D. 4 only

E. All of the above

The correct answer is (D).

Comments:

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, tht is inserted.
4. Correct. This is a dehydration reaction.

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Last modified 1/5/95