Question 10 of 13
The answer you chose is highlighted in reverse video. The correct answer is in bold.
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.
Return to Question Document
jb
Last modified 1/5/95