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*Chemistry Extern > 6.5 Proteins, Electrophoresis, and Lipids > Flashcards

6.5 Proteins, Electrophoresis, and Lipids Flashcards

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1
Q

The Kjeldahl procedure for total protein is based on the premise that:
A. Proteins are negatively charged
B. The pKa of proteins is the same
C. The nitrogen content of proteins is constant
D. Proteins have similar tyrosine and tryptophan content

A

C. The nitrogen content of proteins is constant

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2
Q

The biuret method is based on which principle?
A. The reaction of phenolic groups with CuIISO4
B. Coordinate bonds between Cu+2 and carbonyl and imine groups of peptide bonds
C. The protein error of indicator effect producing color when dyes bind protein
D. The reaction of phosphomolybdic acid with protein

A

B. Coordinate bonds between Cu+2 and carbonyl and imine groups of peptide bonds

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3
Q

Which statement about the biuret reaction for total protein is true?
A. It is sensitive to protein levels below 0.1 mg/dL
B. It is suitable for urine, exudates, and transudates
C. Polypeptides and compounds with repeating imine groups react
D. Hemolysis will not interfere

A

C. Polypeptides and compounds with repeating imine groups react

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4
Q

Which of the following protein methods has the highest analytical sensitivity?
A. Refractometry
B. Folin-Lowry
C. Turbidimetry
D. Direct ultraviolet absorption

A

B. Folin-Lowry

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5
Q

Which of the following statements regarding proteins is true?
A. Total protein and albumin are about 10% higher in ambulatory patients
B. Plasma total protein is about 20% higher than serum levels
C. Albumin normally accounts for about one third of the CSF total protein
D. Transudative serous fluid protein is about two-thirds of the serum total protein

A

A. Total protein and albumin are about 10% higher in ambulatory patients

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6
Q

Hyperalbuminemia is caused by:
A. Dehydration syndromes
B. Liver disease
C. Burns
D. Gastroenteropathy

A

A. Dehydration syndromes

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7
Q

High serum total protein but low albumin is usually seen in:
A. Multiple myeloma
B. Hepatic cirrhosis
C. Glomerulonephritis
D. Nephrotic syndrome

A

A. Multiple myeloma

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8
Q

Which of the following conditions is most commonly associated with an elevated level of total protein?
A. Glomerular disease
B. Starvation
C. Liver failure
D. Malignancy

A

D. Malignancy

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9
Q

Which of the following dyes is the most specific for measurement of albumin?
A. Bromcresol green (BCG)
B. Bromcresol purple (BCP)
C. Tetrabromosulfophthalein
D. Tetrabromphenol blue

A

B. Bromcresol purple (BCP)

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10
Q

Which of the following factors is most likely to cause a falsely low result when using the BCG dye–binding assay for albumin?
A. The presence of penicillin
B. An incubation time of 120 seconds
C. The presence of bilirubin
D. Lipemia

A

A. The presence of penicillin

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11
Q

At pH 8.6, proteins are __________ charged and migrate toward the ________.
A. Negatively, anode
B. Positively, cathode
C. Positively, anode
D. Negatively, cathode

A

A. Negatively, anode

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12
Q

Electrophoretic movement of proteins toward the anode will decrease by increasing the:
A. Buffer pH
B. Ionic strength of the buffer
C. Current
D. Voltage

A

B. Ionic strength of the buffer

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13
Q

At pH 8.6, the cathodal movement of γ globulins is caused by:
A. Electroendosmosis
B. Wick flow
C. A net positive charge
D. Cathodal sample application

A

A. Electroendosmosis

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14
Q

Which of the following conditions will prevent any migration of proteins across an electrophoretic support medium, such as agarose?
A. Using too high a voltage
B. Excessive current during the procedure
C. Loss of contact between a buffer chamber and the medium
D. Evaporation of solvent from the surface of the medium

A

C. Loss of contact between a buffer chamber and the medium

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15
Q

Which of the following proteins has the highest pI?
A. Albumin
B. Transferrin
C. Ceruloplasmin
D. Immunoglobulin G (IgG)

A

D. Immunoglobulin G (IgG)

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16
Q

Which of the following proteins migrates in the β region at pH 8.6?
A. Haptoglobin
B. Orosomucoprotein
C. Antichymotrypsin
D. Transferrin

A

D. Transferrin

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17
Q

Which of the following is one advantage of high-resolution (HR) agarose electrophoresis over lower-current electrophoresis?
A. HR procedures detect monoclonal and oligoclonal bands at a lower concentration
B. A smaller sample volume is used
C. Results are obtained more rapidly
D. Densitometric scanning of HR gels is more accurate

A

A. HR procedures detect monoclonal and oligoclonal bands at a lower concentration

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18
Q

Which of the following conditions is associated with “β-γ bridging”?
A. Multiple myeloma
B. Malignancy
C. Hepatic cirrhosis
D. Rheumatoid arthritis

A

C. Hepatic cirrhosis

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19
Q

Which support medium can be used to determine the molecular weight of a protein?
A. Cellulose acetate
B. Polyacrylamide gel
C. Agar gel
D. Agarose gel

A

B. Polyacrylamide gel

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20
Q

Which of the following stains is used for lipoprotein electrophoresis?
A. Oil Red O
B. Coomassie Brilliant Blue
C. Amido Black
D. Ponceau S

A

A. Oil Red O

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21
Q

Which of the following serum protein electrophoresis results suggests an acute inflammatory process?
Albumin [α1] α2 {β} γ
A. Decreased [Increased] Decreased {Normal} Normal
B. Normal [Increased] Normal {Increased} Increased
C. Decreased [Increased] Increased {Normal} Normal
D. Increased [Increased] Increased {Increased} Increased

A

C. Decreased [Increased] Increased {Normal} Normal

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22
Q

The electrophoretic pattern shown in the following densitometric tracing (shaded gray area) most likely indicates:
A. α1-Antitrypsin deficiency
B. Infection
C. Nephrosis
D. Systemic sclerosis

A

A. α1-Antitrypsin deficiency

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22
Q

Which of the following conditions is usually associated with an acute inflammatory pattern?
A. Myocardial infarction (MI)
B. Malignancy
C. Rheumatoid arthritis
D. Hepatitis

A

A. Myocardial infarction (MI)

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23
Q

What is the clinical utility of testing for serum prealbumin?
A. Low levels are associated with increased free cortisol
B. High levels are an indicator of acute inflammation
C. Serial low levels indicate compromised nutritional status
D. Levels correlate with glomerular injury in patients with diabetes mellitus

A

C. Serial low levels indicate compromised nutritional status

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24
Q

Which serum protein should be measured in a patient suspected of having Wilson disease?
A. Hemopexin
B. α1-Antitrypsin
C. Haptoglobin
D. Ceruloplasmin

A

D. Ceruloplasmin

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25
Q

A patient with hemolytic–uremic syndrome associated with septicemia has a haptoglobin level that is normal, although the plasma free Hgb is elevated and hemoglobinuria is present. Which test would be more appropriate than haptoglobin to measure this patient’s hemolytic episode?
A. Hemopexin
B. α1-Antitrypsin
C. C-reactive protein (CRP)
D. Transferrin

A

A. Hemopexin

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26
Q

Quantitative determination of HgbA2 and Hgb F are best performed by:
A. High-performance liquid chromatography
B. Alkali denaturation
C. Electrophoresis
D. Direct bichromatic spectrophotometry

A

A. High-performance liquid chromatography

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27
Q

Select the correct order of Hgb migration on agarose or cellulose acetate at pH 8.6.
A. – C→F→S→A +
B. – S→C→A→F +
C. – C→S→F→A +
D. – S→F→A→C +

A

C. – C→S→F→A +

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28
Q

Which of the following abnormal types of Hgb migrates to the same position as Hgb S on agarose or cellulose acetate at pH 8.6?
A. Hgb C
B. Hgb DPunjab
C. Hgb OArab
D. Hgb E

A

B. Hgb DPunjab

29
Q

Which Hgb is a β-δ chain hybrid and migrates to the same position as Hgb S at pH 8.6?
A. Hgb CHarlem
B. HgbLepore
C. Hgb GPhiladelphia
D. Hgb DPunjab

A

B. HgbLepore

30
Q

Select the correct order of Hgb migration on citrate agar at pH 6.2.
A. – F→S→C→A +
B. – F→A→S→C +
C. – A→S→F→C +
D. – A→C→S→F +

A

B. – F→A→S→C +

31
Q

Which Hgb separates from Hgb S on citrate (acid) agar, but not agarose or cellulose acetate?
A. Hgb DPunjab
B. Hgb E
C. Hgb CHarlem (Georgetown)
D. Hgb OArab

A

A. Hgb DPunjab

32
Q

Which statement best describes immunofixation electrophoresis (IFE)?
A. Proteins are separated by electrophoresis followed by overlay of monospecific antiimmunoglobulins
B. Proteins react with monospecific antisera followed by electrophoresis
C. Antisera are electrophoresed and then diffused against the patient’s serum
D. Serum is electrophoresed; the separated immunoglobulins diffuse against specific antisera placed into troughs

A

A. Proteins are separated by electrophoresis followed by overlay of monospecific antiimmunoglobulins

33
Q

In double immunodiffusion reactions, the precipitin band is:
A. Invisible before the equivalence point is reached
B. Concave to the protein of greatest molecular weight
C. Closest to the well containing the highest level of antigen
D. Located in an area of antibody excess

A

B. Concave to the protein of greatest molecular weight

34
Q

Which of the following statements regarding the identification of monoclonal proteins by IFE is true?
A. The monoclonal band must be present in the γ region
B. When testing for a monoclonal gammopathy, both serum and urine must be examined
C. A diagnosis of monoclonal gammopathy is based upon quantitation of IgG, IgA, and IgM
D. A monoclonal band always indicates a malignant disorder

A

B. When testing for a monoclonal gammopathy, both serum and urine must be examined

35
Q

Which of the following statements regarding paraproteins is true?
A. Oligoclonal banding is seen in the CSF of greater than 90% of patients with multiple sclerosis
B. The Bence-Jones protein heat test is confirmatory for monoclonal light chains
C. Light chains found in urine are always derived from monoclonal protein
D. The IgA band is usually cathodal to the IgG precipitin band

A

B. The Bence-Jones protein heat test is confirmatory for monoclonal light chains

36
Q

Which statement regarding IFE is true?
A. Serum containing a monoclonal protein should have a κ:λ ratio of 0.5
B. A monoclonal band seen with monospecific antiserum should not be visible in the lane where polyvalent antiserum or sulfosalicylic acid was added
C. CSF should be concentrated 50- to100-fold before performing IFE
D. When oligoclonal bands are seen in CSF, they must also be present in serum to indicate multiple sclerosis

A

C. CSF should be concentrated 50- to100-fold before performing IFE

37
Q

Which test is the most sensitive in detecting early monoclonal gammopathies?
A. HR serum protein electrophoresis
B. Urinary electrophoresis for monoclonal light chains
C. Capillary electrophoresis of serum and urine
D. Serum-free light chain immunoassay

A

D. Serum-free light chain immunoassay

38
Q

Which test is the most useful way to evaluate the response to treatment for multiple myeloma?
A. Measure of total immunoglobulin
B. Measurement of 24-hour urinary light chain concentration (Bence-Jones protein)
C. Capillary electrophoresis to detect M-protein recurrence
D. Measurement of serum-free light chains

A

D. Measurement of serum-free light chains

39
Q

Which of the following is more commonly associated with a MGUS?
A. Bone marrow plasma cells comprise 20% of nucleated cells
B. Monoclonal protein (M-protein) concentration is 3.5 g/dL
C. M-protein is IgG
D. Age greater than 60 at the time of monoclonal protein discovery

A

D. Age greater than 60 at the time of monoclonal protein discovery

40
Q

Capillary electrophoresis differs from agarose gel electrophoresis in which respect?
A. A stationary support is not used
B. An acidic buffer is used
C. A low voltage is used
D. Electroendosmosis does not occur

A

A. A stationary support is not used

41
Q

Select the order of mobility of lipoproteins electrophoresed on agarose at pH 8.6.
A. – Chylomicrons→pre-β→β→α+
B. – β→pre-β→α→chylomicrons +
C. – Chylomicrons→β→pre-β→α +
D. – α→β→pre-β→chylomicrons +

A

C. – Chylomicrons→β→pre-β→α +

42
Q

Following ultracentrifugation of plasma, which fraction correlates with pre-β lipoprotein?
A. Very low-density lipoprotein (VLDL)
B. Low-density lipoprotein (LDL)
C. High-density lipoprotein (HDL)
D. Chylomicrons

A

A. Very low-density lipoprotein (VLDL)

43
Q

Select the lipoprotein fraction that carries most of the endogenous triglycerides.
A. VLDL
B. LDL
C. HDL
D. Chylomicrons

A

A. VLDL

44
Q

The protein composition of HDL is what percentage by weight?
A. Less than 2%
B. 25%
C. 50%
D. 90%

A

C. 50%

45
Q

Which apoprotein is inversely related to risk of coronary heart disease?
A. Apoprotein A-I
B. Apoprotein B-100
C. Apoprotein C-II
D. Apoprotein E4

A

A. Apoprotein A-I

46
Q

Which lipoprotein accumulates in familial β dyslipoproteinemia?
A. Chylomicrons
B. VLDL
C. IDL
D. HDL

A

C. IDL

47
Q

Which of the following mechanisms accounts for the elevated plasma level of β lipoproteins seen in familial hypercholesterolemia?
A. Hyperinsulinemia
B. ApoB-100 receptor defect
C. ApoC-II activated lipase deficiency
D. ApoE3 deficiency

A

B. ApoB-100 receptor defect

48
Q

Which enzyme deficiency is most commonly associated with familial hypertriglyceridemia associated with fasting plasma cholomicrons?
A. β-Glucocerebrosidase deficiency
B. Post–heparin-activated lipoprotein lipase deficiency
C. Apo B deficiency
D. Apo C-III deficiency

A

B. Post–heparin-activated lipoprotein lipase deficiency

49
Q

Which of the following conditions is most consistently associated with secondary hypercholesterolemia?
A. Hypothyroidism
B. Pancreatitis
C. Oral contraceptive therapy
D. Diabetes mellitus

A

A. Hypothyroidism

50
Q

Which of the following is associated with Tangier disease?
A. Apoprotein C-II deficiency
B. Homozygous apo B-100 deficiency
C. Apoprotein C-II activated lipase
D. Apoprotein A-I deficiency

A

D. Apoprotein A-I deficiency

51
Q

Which of the following statements is correct?
A. Both HDL and LDL are homogenous
B. There are several subfractions of LDL but not HDL
C. There are several subfractions of HDL but not LDL
D. There are several subfractions of both HDL and LDL

A

D. There are several subfractions of both HDL and LDL

52
Q

What is the lipid testing protocol for adults recommended by the National Cholesterol Education Program (NCEP) to evaluate risk for atherosclerosis beginning at age 20 years?
A. Total cholesterol every year
B. Total cholesterol every 2 years
C. Lipid profile every 5 years
D. LDL cholesterol every 2 years

A

C. Lipid profile every 5 years

53
Q

What is the most appropriate procedure when a fasting lipid study of triglyceride, total cholesterol, HDL cholesterol, and LDL cholesterol tests are ordered?
A. 8 hours; nothing but water allowed
B. 10 hours; water, smoking, coffee, tea (no sugar or cream) allowed
C. 12 hours; nothing but water allowed
D. 16 hours; water, smoking, coffee, tea (no sugar or cream) allowed

A

C. 12 hours; nothing but water allowed

54
Q

Treatment recommendations for patients with coronary heart disease are based on the measurement of which analyte?
A. HDL cholesterol
B. Apo B-100
C. LDL cholesterol
D. Total cholesterol

A

C. LDL cholesterol

55
Q

What is the HDL cholesterol cutoff that constitutes a risk factor for CAD as recommend by NCEP?
A. Less than 30 mg/dL
B. Less than 40 mg/dL
C. Less than 30 mg/dL for males and less than 40 mg/dL for females
D. Less than 45 mg/dL for males and less than 50 mg/dL for females

A

B. Less than 40 mg/dL

56
Q

An EDTA blood sample is collected from a nonfasting person for a complete blood count (CBC). The physician collected the sample from the femoral vein because venipuncture from the arm was unsuccessful. He called the laboratory 15 minutes after the sample arrived and requested a lipid study, including triglyceride, total cholesterol, HDL cholesterol, and LDL cholesterol. Which test results should be used to evaluate the patient’s risk for CAD?
A. Total cholesterol and LDL cholesterol
B. LDL cholesterol and triglyceride
C. Total cholesterol and HDL cholesterol
D. All four lipid results can be used if the nonfasting triglyceride level is less than 200 mg/dL

A

D. All four lipid results can be used if the nonfasting triglyceride level is less than 200 mg/dL

57
Q

Which mutation results in high levels of LDL cholesterol?
A. Lipoprotein lipase (LPL)
B. Apoprotein A1 (APOA1)
C. Proprotein convertase subtilisin/kexin type 9 (PCSK9)
D. Lipin1 (LPIN1)

A

C. Proprotein convertase subtilisin/kexin type 9 (PCSK9)

58
Q

Which of the following diseases is caused by a deficiency of sphingomyelinase?
A. Gaucher disease
B. Fabry disease
C. Niemann-Pick disease
D. Tay-Sachs disease

A

C. Niemann-Pick disease

59
Q

Which of the following enzymes is common to all enzymatic methods for triglyceride measurement?
A. Glycerol phosphate oxidase
B. Glycerol phosphate dehydrogenase
C. Glycerol kinase
D. Pyruvate kinase

A

C. Glycerol kinase

60
Q

Select the reagent needed in the coupling enzyme reaction used to generate a colored product in the cholesterol oxidase method for cholesterol.
A. Cholestahexaene
B. H2O2
C. 4-Aminoantipyrine
D. Cholest-4-ene-3-one

A

C. 4-Aminoantipyrine

61
Q

What is the purpose of the saponification step used in the Abell-Kendall method for cholesterol measurement?
A. Remove phospholipids
B. Reduce sterol molecules structurally similar to cholesterol
C. Convert cholesterol esters to free cholesterol
D. Remove proteins that can interfere with color formation

A

C. Convert cholesterol esters to free cholesterol

62
Q

Which of the following methods for HDL cholesterol is the reference method?
A. Selective inhibition by anti-apo B-100 and apo CII
B. Magnesium–phosphotungstate precipitation
C. Magnesium–dextran precipitation
D. Ultracentrifugation followed by manganese-heparin precipitation

A

D. Ultracentrifugation followed by manganese-heparin precipitation

63
Q

Cholesterol esterase is used in enzymatic assays to:
A. Oxidize cholesterol to form peroxide
B. Hydrolyze fatty acids bound to the third carbon atom of cholesterol
C. Separate cholesterol from apoproteins A-I and A-II by hydrolysis
D. Reduce NAD+ to NADH

A

B. Hydrolyze fatty acids bound to the third carbon atom of cholesterol

64
Q

Which of the following reagents is used in the direct HDL cholesterol method?
A. Sulfated cyclodextrin
B. Magnesium sulfate and dextran sulfate
C. Anti-apoA-I
D. Manganese heparin

A

A. Sulfated cyclodextrin

65
Q

What do “direct” or homogenous methods for LDL cholesterol assay have in common?
A. They are inaccurate when plasma triglyceride is above 250 mg/dL
B. All use a detergent to facilitate selective reactivity with reagent enzymes
C. All use monoclonal antibodies to apo A-1 and apo C
D. All are free of interference from abnormal lipoproteins

A

B. All use a detergent to facilitate selective reactivity with reagent enzymes

66
Q

Lipoprotein (a), or Lp(a), is significant when elevated in serum because it:
A. Is an independent risk factor for atherosclerosis
B. Blocks the clearance of VLDLs
C. Displaces apo A-I from HDLs
D. Is linked closely to a gene for obesity

A

A. Is an independent risk

67
Q

Which type of dietary fatty acid is not associated with an increase in serum LDL cholesterol production?
A. Monounsaturated trans fatty acids
B. Saturated fatty acids
C. Monounsaturated cis fatty acids
D. Monounsaturated trans Ω-9 fatty acids

A

C. Monounsaturated cis fatty acids

68
Q

SITUATION: A lipemic specimen collected from an adult after a 12-hour fast was assayed for total cholesterol, triglycerides, and HDL cholesterol by using a direct HDL method. Following are the results:
Total cholesterol = 220 mg/Dl
HDL cholesterol = 40 mg/dL
Triglyceride = 420 mg/dL
The physician requests an LDL cholesterol assay after receiving the results. How should the LDL cholesterol be determined?
A. Dilute the specimen 1:10 and repeat all tests. Calculate LDL cholesterol using the Friedewald equation
B. Perform a direct LDL cholesterol assay
C. Ultracentrifuge the sample and repeat the HDL cholesterol on the infranate. Use the new result to calculate the LDL cholesterol
D. Repeat the HDL cholesterol using the manganese–heparin precipitation method. Use the new result to calculate the LDL cholesterol

A

B. Perform a direct LDL cholesterol assay

69
Q

A person has a fasting triglyceride level of 240 mg/dL. The physician wishes to know the patient’s non-HDL cholesterol level. What cholesterol fractions should be measured?
A. Total cholesterol and HDL cholesterol
B. Total cholesterol and LDL cholesterol
C. HDL cholesterol and LDL cholesterol
D. Total cholesterol and chylomicrons

A

A. Total cholesterol and HDL cholesterol

*Chemistry Extern (18 decks)

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