Porphyrins and Hemoglobin Flashcards
The primary purpose of porphyrins in the human body is to
a. Chelate free hemoglobin
b. Contribute to the synthesis of heme
c. Transport ferrous iron
d. Transport oxygen to tissues
b. Contribute to the synthesis of heme
The chemical structure of porphyrin is described as a(n)
a. Cyclic tetrapyrrole
b. Heterocyclic pyrrole
c. Linear tetrapyrrole
d. Oxygen-binding prosthetic group
a. Cyclic tetrapyrrole
Which statement correctly describes a porphyrin property?
a. Porphyrins absorb light in the visible region of the spectrum and
fluoresce.
b. Porphyrins are not soluble in aqueous solution.
c. Porphyrins are oxidized to porphyrinogens when exposed to air.
d. Porphyrins produced spontaneously are functional compounds.
a. Porphyrins absorb light in the visible region of the spectrum and
fluoresce.
The porphyrias can be classified according to disease symptoms as
a. Congenital or acquired
b. Erythropoietic or hepatic
c. Hematologic or muscular
d. Neurologic or cutaneous
d. Neurologic or cutaneous
Elevated urinary PBG concentration with negative fecal porphyrin results
indicates
a. Acute intermittent porphyria (AIP)
b. Erythropoietic protoporphyria (EPP)
c. Hereditary coproporphyria (HCP)
d. Porphyria cutanea tarda (PCT)
a. Acute intermittent porphyria (AIP)
Porphyria cutanea tarda (PCT) is identified by
a. Chromatographic analysis of a 24-h urine collection
b. Scanning fluorescence of plasma
c. Screening for PBG in a random urine specimen
d. Separation of fecal porphyrins in a 24-h specimen
a. Chromatographic analysis of a 24-h urine collection
Suspected erythropoietic protoporphyria (EPP) is evaluated by
a. Assessing plasma or whole blood for protoporphyrin
b. Enzymatic measurement of hydroxymethylbilane synthase
c. HPLC analysis of a urine specimen
d. Molecular testing for ferrochelatase
a. Assessing plasma or whole blood for protoporphyrin
Porphobilinogen often is measured in the urine using
a. Chromatography
b. Electrophoresis
c. Spectrophotometry
d. The Watson-Schwartz method
d. The Watson-Schwartz method
In the clinical laboratory, testing to identify specific porphyrins is performed
using
a. Chemical derivatization and spectrophotometry
b. Fluorometric emission scanning
c. Liquid chromatography with fluorescent detection
d. Thin layer chromatography
a. Chemical derivatization and spectrophotometry
Specimens collected for evaluation of porphyria should be
a. Allowed to clot at room temperature for an hour
b. Diluted to less than 25 mg/dL creatinine
b. Exposed to light and air to oxidize the analytes
d. Protected from light and stored cold
d. Protected from light and stored cold
Inherited disorders in which a genetic defect causes abnormalities in rate and
quantity of synthesis of structurally normal polypeptide chains of the
hemoglobin molecule are called
a. Hemoglobinopathies
b. Molecular dyscrasias
c. Porphyrias
d. Thalassemias
d. Thalassemias
Molecular diagnostic techniques that can help diagnose hemoglobin
disorders such as hemoglobinopathies and thalassemias include
a. Biochemical separation, identification, and quantification of mixture
components
b. Separation of macromolecules and their fragments, based on their size
and charge
c. DNA amplification, hybridization, and nucleotide sequencing
d. The use of specific monoclonal antibodies
c. DNA amplification, hybridization, and nucleotide sequencing
Which of the following abnormal hemoglobins, found frequently in
individuals from Southeast Asia, migrates with hemoglobin A2 on
cellulose acetate electrophoresis?
a. Hemoglobin C
b. Hemoglobin D
c. Hemoglobin E
d. Hemoglobin Lepore
c. Hemoglobin E
Which type of alpha-thalassemia results from deletion of three genes and
produces a moderate hemolytic anemia?
a. Hemoglobin Bart’s
b. Hemoglobin H disease
c. Hydrops fetalis
d. Thalassemia trait
b. Hemoglobin H disease
The most effective way to quantitate hemoglobin A2
is by
a. Alkali denaturation test
b. Citrate agar electrophoresis
c. Column chromatography
d. Densitometry
c. Column chromatography
Serum or plasma myoglobin Concentrations are used as
a. An early marker of acute myocardial infarction
b. An indicator of congestive heart failure
c. Lead poisoning indicator
d. Liver function tests
a. An early marker of acute myocardial infarction
Which of the following is the best test to differentiate beta-thalassemia minor
from iron deficiency anemia?
a. Complete blood count
b. Hemoglobin A2 quantitation
c. Hemoglobin electrophoresis (cellulose acetate, alkaline pH)
d. Solubility test
b. Hemoglobin A2 quantitation
Which is the correct sequence of electrophoretic migration of hemoglobins
from slowest to fastest on cellulose acetate at an alkaline pH?
a. A, F, S, C
b. C, A, S, F
c. C, S, A, F
d. C, S, F, A
d. C, S, F, A
High-resolution melting (HRM) is a technique that can be used post PCR
amplification as long as the probe utilized during the amplification process
is complexed with a fluorescent detection dye that recognizes
a. Single-stranded DNA
b. Double-stranded DNA
c. cDNA
d. Specific primers
b. Double-stranded DNA
The two main sites of production of heme are
a. Heart and lung
b. Liver and bone marrow
c. Liver and spleen
d. Muscle and blood
b. Liver and bone marrow
Which hemoglobin is resistant to alkali denaturation in NaOH?
a. Hb A
b. Hb C
c. Hb F
d. Hb S
c. Hb F
A patient has an abnormal hemoglobin band that migrates with Hb S on
cellulose acetate (pH 8.4) hemoglobin electrophoresis. The solubility test is
negative. Which test should be performed next?
a. Citrate agar (pH 6.2) electrophoresis
b. HbA2 quantitation
c. Acid elution stain
d. Blood film evaluation
a. Citrate agar (pH 6.2) electrophoresis
Silent carriers of alpha-thalassemia are missing how many alpha genes?
a. 1
b. 2
c. 3
d. 4
a. 1
Which hemoglobin contains four gamma chains and has an extremely high
affinity for oxygen?
a. Hb Bart’s
b. Hb F
c. Hb Gower I
d. Hb Portland I
a. Hb Bart’s
A patient with Southeast Asian heritage is found to have a mild microcytic
anemia and a few target cells. Hemoglobin electrophoresis on cellulose
acetate at pH 8.4 reveals a major band that migrates with Hb A2 and no Hb
A. On citrate agar electrophoresis, the band travels in the position of Hb A.
What is the most probable abnormal hemoglobin present?
a. Hb A
b. Hb C
c. Hb D
d. Hb E
d. Hb E
