Heme and Iron Quiz
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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.
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Protoporphyrin IX.
- A. Intermediate in heme synthesis
- B. Intermediate in heme degradation
- 1. A only
- 2. B only
- 3. Both A and B
- 4. Neither A or B
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Coproporphyrinogen I.
- A. Intermediate in heme synthesis
- B. Intermediate in heme degradation
- 1. A only
- 2. B only
- 3. Both A and B
- 4. Neither A or B
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A patient with blockage of hepatic biliary network.
- A. Increased "Indirect" bilirubin in patient's blood
- B. Increased "Direct" bilirubin in patient's blood
- 1. A only
- 2. B only
- 3. Both A and B
- 4. Neither A or B
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A patient with decreased hepatic uptake of bilirubin.
- A. Increased "Indirect" bilirubin in patient's blood
- B. Increased "Direct" bilirubin in patient's blood
- 1. A only
- 2. B only
- 3. Both A and B
- 4. Neither A or B
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In hereditary protoporphyria, which enzyme of heme synthesis
is decreased?
- A. Coproporphyrinogen oxidase
- B. Ferrochelatase
- C. Porphobilinogen synthase
- D. Uroporphyrinogen oxidase
- E. Uroporphyrinogen synthase
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Porphobilinogen synthase (delta-aminolevulinic acid dehydratase):
- 1. is the control step in heme synthesis.
- 2. is inhibited by lead.
- 3. requires pyridoxal (vitamin B6) phosphate for activity.
- 4. is present in the cytosol.
- A. 1, 2 and 3
- B. 1 and 3
- C. 2 and 4
- D. 4 only
- E. All of the above
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Contain(s) propionic acid and acetic acid side chains on pyrrole rings
- A. Uroporphyrinogen I
- B. Uroporphyrin III
- 1. A only
- 2. B only
- 3. Both A and B
- 4. Neither A or B
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Formed directly by the condensation of porphobilinogens
- A. Uroporphyrinogen I
- B. Uroporphyrin III
- 1. A only
- 2. B only
- 3. Both A and B
- 4. Neither A or B
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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
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A rise in serum "direct" bilirubin would be expected in:
- 1. hemolytic jaundice.
- 2. absence of glucuronyl transferase as in the newborn.
- 3. decreased hepatic uptake of bilirubin (Gilbert's Disease).
- 4. biliary obstruction.
- A. 1, 2 and 3
- B. 1 and 3
- C. 2 and 4
- D. 4 only
- E. All of the above
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In iron metabolism:
- 1. iron stored in liver cells is transported across cell membranes in the ferrous state.
- 2. the major plasma transport protein for iron is hemosiderin.
- 3. in the form of ferritin, iron may accumulate in mucosal
cells of the duodenum.
- 4. nearly all iron in the diet is absorbed and any excess
secreted in the feces.
- A. 1, 2 and 3
- B. 1 and 3
- C. 2 and 4
- D. 4 only
- E. All of the above
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Delta-aminolevulinic acid synthase:
- 1. requires pyridoxal phosphate for activity.
- 2. synthesis can be induced by phenobarbital and some
steroids.
- 3. is inhibited by heme.
- 4. is inhibited by lead.
- A. 1, 2 and 3
- B. 1 and 3
- C. 2 and 4
- D. 4 only
- E. All of the above
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Last modified 1/5/95