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BOC Book > Enzymes (Chemistry) > Flashcards

Enzymes (Chemistry) Flashcards

1
Q

The most specific enzyme for acute pancreatitis is:

A) acid phosphatase
B) trypsin
C) amylase
D) lipase

A

D) lipase

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2
Q

Which of the following enzymes are used in the diagnosis of acute pancreatitis?

A) amylase (AMS)
B) aspartate aminotransferase (AST)
C) gamma-glutamyl transferase (GGT)
D) lactate dehydrogenase (LD)

A

A) amylase (AMS)

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3
Q

Which of the following enzymes catalyzes the conversion of starch to glucose and maltose?

A) malate dehydrogenase (MD)
B) amylase (AMS)
C) creatine kinase (CK)
D) isocitric dehydrogenase (ICD)

A

B) amylase (AMS)

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4
Q

Which of the following sets of results would be consistent with macroamylasemia?

A) normal serum amylase and elevated urine amylase values
B) increased serum amylase and normal urine amylase values
C) increased serum and urine amylase values
D) normal serum and urine amylase values

A

B) increased serum amylase and normal urine amylase values

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5
Q

In acute pancreatitis, the following results would be expected:

A) LD isoenzymes 1 elevates higher than 2 within 72 hours
B) lipase elevates within 4-8 hours of an attack, peaks at 24 hours and normalizes in 48 hours
C) amylase and lactate rise successively in the first 24 hours and stay elevated 4 days
D) amylase and lipase elevate in a few hours, but amylase normalizes within 3 days

A

D) amylase and lipase elevate in a few hours, but amylase normalizes within 3 days

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6
Q

Aspartate amino transferase (AST) is characteristically elevated in diseases of the:

A) liver
B) kidney
C) intestine
D) pancreas

A

A) liver

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7
Q

Amino transferase enzymes catalyze the:

A) exchange of amino groups and sulfhydryl groups between alpha-amino and sulfur-containing acids
B) exchange of amino and keto groups between alpha-amino and alpha-keto acids
C) hydrolysis of amino acids and keto acids
D) reversible transfer of hydrogen from amino acids to coenzyme

A

B) exchange of amino and keto groups between alpha-amino and alpha-keto acids

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8
Q

Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are both elevated in which of the following diseases?

A) muscular dysrophy
B) viral hepatitis
C) pulmonary emboli
D) infectious mononucleosis

A

B) viral hepatitis

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9
Q

Interpretation of and sources of interference in serum enzyme analysis should consider that a significant source of ______________ is found in RBCs.

A) AST
B) ALT
C) GGT
D) CK

A

A) AST

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10
Q

Malic dehydrogenase is added to the aspartate aminotransaminase (AST) reaction to catalyze the conversion of:

A) alpha-ketoglutarate to aspartate
B) alpha-ketoglutarate to malate
C) aspartate to oxalacetate
D) oxalacetate to malate

A

D) oxalacetate to malate

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11
Q

Given the following results:

alkaline phosphatase: slight increase
aspartate amino transferase: marked increase
alanine amino transferase: marked increase
gamma-glutamyl transferase: slight increase

This is most consistent with:

A) acute hepatitis
B) chronic hepatitis
C) obstructive jaundice
D) liver hemangioma

A

A) acute hepatitis

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12
Q

Which of the following clinical disorders is associated with the greatest elevation of lactate dehydrogenase isoenzyme 1?

A) pneumonia
B) glomerulonephritis
C) pancreatitis
D) pernicious anemia

A

D) pernicious anemia

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13
Q

The enzyme, which exists chiefly in skeletal muscle, heart, and brain, is grossly elevated in active muscular dystrophy, and rises early in myocardial infarction is:

A) lipase
B) transaminase
C) lactate dehydrogenase
D) creatine kinase

A

D) creatine kinase

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14
Q

The enzyme present in almost all tissue that may be separated by electrophoresis into 5 components is:

A) lipase
B) transaminase
C) creatine kinase
D) lactate dehydrogenase

A

D) lactate dehydrogenase

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15
Q

A common cause of a falsely increased LD1 fraction of lactic dehydrogenase is:

A) specimen hemolysis
B) liver disease
C) congestive heart failure
D) drug toxicity

A

A) specimen hemolysis

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16
Q

The presence of which of the following isoenzymes indicates acute myocardial damage?

A) CKMM
B) CKMB
C) CKBB
D) none

A

B) CKMB

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17
Q

In which of the following conditions would a normal level of creatine kinase be found?

A) acute myocardial infarct
B) hepatitis
C) progressive muscular dystrophy
D) intramuscular injection

A

B) hepatitis

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18
Q

Of the following diseases, the one most often associated with elevations of lactate dehydrogenase isoenzymes 4 and 5 on electrophoresis is:

A) liver disease
B) hemolytic anemia
C) myocardial infarction
D) pulmonary edema

A

A) liver disease

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19
Q

When myocardial infarction occurs, the first enzyme to become elevated is:

A) CK
B) LD
C) AST
D) ALT

A

A) CK

20
Q

A scanning of a CK isoenzyme fractionation revealed 2 peaks: a slow cathodic peak (CKMM) and an intermediate peak (CKMB). A possible interpretation for this patter is:

A) brain tumor
B) muscular dystrophy
C) myocardial infarction
D) viral hepatitis

A

C) myocardial infarction

21
Q

An electrophoretic separation of lactate dehydrogenase isoenzymes that demonstrates an elevation in LD-1 and LD-2 in a “flipped” pattern is consistent with:

A) myocardial infarction
B) viral hepatitis
C) pancreatitis
D) renal failure

A

A) myocardial infarction

22
Q

Increased total serum LD activity is:

A) sensitive and specific to acute myocardial infarction
B) specific to acute hepatic disease such as viral hepatitis
C) sensitive to pancreatic obstruction but not pancreatitis
D) sensitive but not specific to neoplastic disease

A

D) sensitive but not specific to neoplastic disease

23
Q

A 10 year old child was admitted to pediatrics with an initial diagnosis of skeletal muscle disease. The best confirmatory tests would be:

A) creatine kinase and isocitrate dehydrogenase
B) gamma-glutamyl transferase and alkaline phosphatase
C) aldolase and creatine kinase
D) lactate dehydrogenase and malate dehydrogenase

A

C) aldolase and creatine kinase

24
Q

In the immunoinhibition phase of the CKMB procedure:

A) M subunit is inactivated
B) B subunit is inactivated
C) MB is inactivated
D) BB is inactivated

A

A) M subunit is inactivated

25
Q

The presence of increased CKMB activity on a CK electrophoresis pattern is most likely found in a patient suffering from:

A) acute muscular stress following strenuous exercise
B) malignant liver disease
C) myocardial infarction
D) severe head injury

A

C) myocardial infarction

26
Q

Increased serum lactic dehydrogenase activity due to elevation of fast fraction (1 and 2) on electrophoretic separation is caused by:

A) nephrotic syndrome
B) hemolytic anemia
C) pancreatitis
D) hepatic damage

A

B) hemolytic anemia

27
Q

A serum sample drawn in the emergency room from a 42-year-old yielded the following laboratory results:

CK
Patient: 185 U/L
Reference Range: 15-160 U/L

AST
Patient: 123 U/L
Reference Range: 0-48 U/L

CKMB
Patient: 6 U/L
Reference Range: 2-12 U/L

Which of the following conditions might account for these values?

A) crush injury to the thigh
B) cerebrovascular accident
C) pulmonary infarction
D) early acute hepatitis

A

A) crush injury to the thigh

28
Q

Given the following results:

alkaline phosphatase: marked increase
aspartate aminotransferase: slight increase
alanine aminotransferase: slight increase
gamma-glutamyl transferase: marked increase

This is most consistent with:

A) acute hepatitis
B) osteitis fibrosa
C) chronic hepatitis
D) obstructive jaundice

A

D) obstructive jaundice

29
Q

Given the following results:

alkaline phosphatase: slight increase
aspartate aminotransferase: slight increase
alanine aminotransferase: slight increase
gamma-glutamyl transferase: marked increase

This is most consistent with:

A) acute hepatitis
B) chronic hepatitis
C) obstructive jaundice
D) liver hemangioma

A

B) chronic hepatitis

30
Q

What specimen preparation is used to perform the alkaline phosphatase isoenzyme determination?

A) serum is divided into 2 aliquots, one is frozen and the other is refrigerated
B) serum is divided into 2 aliquots, one is heated at 56 degrees C and the other is unheated
C) no preparation is necessary since the assay uses EDTA plasma
D) protein-free filtrate is prepared first

A

B) serum is divided into 2 aliquots, one is heated at 56 degrees C and the other is unheated

31
Q

Regan isoenzyme has the same properties as alkaline phosphatase that originates in the:

A) skeleton
B) kidney
C) intestine
D) placenta

A

D) placenta

32
Q

The most heat labile fraction of alkaline phosphatase is obtained from:

A) liver
B) bone
C) intestine
D) placenta

A

B) bone

33
Q

The most sensitive enzymatic indicator for liver damage from ethanol intake is:

A) alanine aminotransferase (ALT)
B) aspartate aminotransferase (AST)
C) gamma-glutamyl transferase (GGT)
D) alkaline phosphatase

A

C) gamma-glutamyl transferase (GGT)

34
Q

Isoenzyme assays are performed to improve:

A) precision
B) accuracy
C) sensitivity
D) specificity

A

D) specificity

35
Q

The protein portion of an enzyme complex is called the:

A) apoenzyme
B) coenzyme
C) holoenzyme
D) proenzyme

A

A) apoenzyme

36
Q

Which of the following chemical determinations may be of help in establishing the presence of seminal fluid?

A) lactic dehydrogenase (LD)
B) isocitrate dehydrogenase (ICD)
C) acid phosphatase
D) alkaline phosphatase

A

C) acid phosphatase

37
Q

Which of the following enzyme substrates is the most specific for prostatic acid phophatase for quantitative endpoint reactions?

A) p-nitrophenylphosphate
B) thymolphthalein monophosphate
C) beta-naphthol-phosphate
D) beta-glycerophophate

A

B) thymolphthalein monophosphate

38
Q

Lactate dehydrogenase, malate dehydrogenase, isocitrate dehydrogenase, and glucose 6 phosphate dehydrogenase all:

A) are liver enzymes
B) are cardiac enzymes
C) catalyze oxidation-reduction reactions
D) are class III enzymes

A

C) catalyze oxidation-reduction reactions

39
Q

Which of the following is the Henderson-Hasselbalch equation?

A) pKa= pH + log([acid]/[salt])
B) pKa= pH + log ([salt]/[acid])
C) pH^a= pHa + log([acid]/[salt])
D) pH = pKa + log([salt]/[acid])

A

D) pH = pKa + log([salt]/[acid])

40
Q

In the assay of lactate dehydrogenase, which of the following products is actually measured?

A) NADH
B) ATP
C) lactic acid
D) pyruvic acid

A

A) NADH

41
Q

In the assay of lactate dehydrogenase (LD), the reaction is dependent upon which of the following coenzyme systems?

A) NAD/NADH
B) ATP/ADP
C) Fe2+/Fe3+
D) Cu/Cu2+

A

A) NAD/NADH

42
Q

In competitive inhibition of an enzyme reaction, the:

A) inhibitor binds to the enzyme at the same site as does the substrate
B) inhibitor often has a chemical structure different to that of the substrate
C) activity of the reaction can be decreased by increasing the concentration of the substrate
D) activity of the reaction can be increased by decreasing the temperature

A

A) inhibitor binds to the enzyme at the same site as does the substrate

42
Q

In competitive inhibition of an enzyme reaction, the:

A) inhibitor binds to the enzyme at the same site as does the substrate
B) inhibitor often has a chemical structure different to that of the substrate
C) activity of the reaction can be decreased by increasing the concentration of the substrate
D) activity of the reaction can be increased by decreasing the temperature

A

A) inhibitor binds to the enzyme at the same site as does the substrate

42
Q

In competitive inhibition of an enzyme reaction, the:

A) inhibitor binds to the enzyme at the same site as does the substrate
B) inhibitor often has a chemical structure different to that of the substrate
C) activity of the reaction can be decreased by increasing the concentration of the substrate
D) activity of the reaction can be increased by decreasing the temperature

A

A) inhibitor binds to the enzyme at the same site as does the substrate

43
Q

In competitive inhibition of an enzyme reaction, the:

A) inhibitor binds to the enzyme at the same site as does the substrate
B) inhibitor often has a chemical structure different to that of the substrate
C) activity of the reaction can be decreased by increasing the concentration of the substrate
D) activity of the reaction can be increased by decreasing the temperature

A

A) inhibitor binds to the enzyme at the same site as does the substrate

44
Q

The most common cause of rapid nonlinerarity following the timed lag phase in an enzyme kinetic assay is resolved by:

A) addition of more coenzyme such as NADH to the reaction following the timed lag phase
B) preventing extraneous protein from binding to the E-S complex by making a protein free during the reaction
C) decreasing the sample volume to dilute the enzyme so that substrate remains in excess during the reaction
D) eliminating metallic ions that may be making structural changes an inhibition to the enzyme active site

A

C) decreasing the sample volume to dilute the enzyme so that substrate remains in excess during the reaction

45
Q

The International Federation for Clinical Chemistry (IFCC) recommends the use of methods such as the Bessey-Lowry-Brock method for determining alkaline phosphatase activity. The substrate used in this type of method is:

A) monophosphate
B) phenylphosphate
C) disodium phenylphophate
D) para-nitrophenylphosphate

A

D) para-nitrophenylphosphate

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