Heme and Iron Quiz

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.

Question 2 of 13

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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

Question 3 of 13

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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

Question 4 of 13

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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

Question 5 of 13

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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

Question 6 of 13

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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

Question 7 of 13

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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

Question 8 of 13

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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

Question 9 of 13

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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

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

Question 11 of 13

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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

Question 12 of 13

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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

Question 13 of 13

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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

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