Deck 10: Enzymes

Question 1

Zero order kinetics results:

A) When there are equal amounts of enzyme and substrate present.
B) When there is more enzyme than substrate present.
C) When all of the available sites on the enzyme are saturated with substrate.
D) When none of the available sites are saturated with substrate.

Answer 1

When all of the available sites on the enzyme are saturated with substrate.

Question 2

Ligases are a class of enzymes that catalyze:

A) Oxidation-reduction reactions.
B) The transfer of groups.
C) The removal of groups without the addition of water.
D) The coupling of two molecules with the use of ATP.

Answer 2

The coupling of two molecules with the use of ATP.

Question 3

Enzymes that catalyze the transfer of groups other than hydrogen between compounds are classified as belonging to which enzyme class?

A) Hydrolases
B) Lyases
C) Oxidoreductases
D) Transferases

Answer 3

Transferases

Question 4

Many enzymes in the blood plasma show maximum activity in which of the following pH ranges?

A) 4 to 5
B) 6 to 7
C) 7 to 8
D) 8 to 9

Question 5

The indicator reaction (what is actually measured) in Oliver-Rosalki is:

A) Adenylate kinase.
B) Pyruvate kinase.
C) Lactate dehydrogenase.
D) The reduction of NADP⁺.

Question 6

Although a total lactate dehydrogenase (LD) determination performed alone yields little information as to the area of tissue destruction, an electrophoretic separation of LD isoenzyme may be useful. With what disorder is an increase in LD-5 and LD-4 associated?

A) Acute hepatic disease
B) Acute myocardial infarction
C) Pulmonary infarction
D) Pancreatitis

Question 7

Aspartate aminotransferase is elevated in diseases involving the:

A) Renal cortex.
B) Heart muscle.
C) Intestinal epithelium.
D) Acinar cells of the pancreas.

Question 8

Malate dehydrogenase (MD) is used in the aspartate transferase reaction mixture to convert:

A) L-glutamate to alpha oxoglutarate.
B) L-glutamate to L-aspartate.
C) L-malate to L-glutamate.
D) Oxaloacetate to L-malate.

Question 9

In which liver disease is the DeRitis ratio (AST: ALT) usually less than or equal to 1?

A) Acute viral hepatitis
B) Cirrhosis
C) Alcoholic hepatitis
D) All of the above

Question 10

The highest levels of alkaline phosphatase are seen in:

A) Obstructive liver disease.
B) Hepatitis.
C) Renal failure.
D) Myocardial infarction.
E) Pancreatitis.

Question 11

Which of the following would NOT show an increase in alkaline phosphatase?

A) Obstructive liver disease (hepatobiliary) rickets
B) Rickets
C) Hemolytic anemia
D) Osteoporosis

Question 12

The most sensitive indicator of alcoholic liver disease is:

A) AST.
B) ALT.
C) ?GT.
D) ALP.

Question 13

Serum lipase catalyzes:

A) Hydrolysis of triglyceride to fatty acids and glycerol.
B) Hydrolysis of triglyceride to fatty acids and water.
C) Synthesis of triglyceride from fatty acids and water.
D) Synthesis of triglyceride from fatty acids and glycerol.

Question 14

A substrate used in lipase reactions is:

A) Starch.
B) ?-nitrophenyl phosphate.
C) Olive oil emulsion.
D) Creatine phosphate.

Question 15

The best test for pancreatitis in the presence of mumps is:

A) Virus isolation.
B) A serologic test for mumps.
C) A urine amylase test.
D) A serum lipase test.

Question 16

Serum chemistry results on a 53-year-old female are
AST: 120 U/L (4-34U/L)
ALT: 185 U/L (5-40 U/L)
ALP: 785 U/L (<165 U/L)
?GT: 225 U/L (5-24 U/L)
Total Bilirubin: 10.8 mg/dL
Direct Bilirubin: 8.6 mg/dL
Urine bilirubin: positive
Urine urobilinogen: Normal
Fecal urobilinogen: decreased
These results are consistent with a diagnosis of:

A) Hemolytic anemia.
B) Hepatitis.
C) Dubin-Johnson.
D) Biliary obstruction.

Question 17

Mrs. Smith has the following chemistry results:
CK: moderately increased
LD: moderately increased
LD-1 : increased
The probable diagnosis is:

A) Myocardial infarction.
B) Acute pancreatitis.
C) Acute hepatitis.
D) Cholecystitis.

Question 18

A patient's CK-MB is reported as 18 ?g/L and the total CK is 560 IU/L. What is the CK relative index (CKI)?

A) 0.10%
B) 3.2%
C) 10.0%
D) 30.0%

Question 19

The prostatic fraction of acid phosphatase is inhibited by:

A) Acetic acid.
B) Citric acid.
C) Sodium nitrite.
D) Tartrate.

Question 20

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

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

Question 21

Cholinesterase catalyzes the conversion of:

A) Choline to lecithin.
B) Acetylcholine to choline and acetic acid.
C) Choline to NH₄⁺ and PO₄^-3.
D) ?-glycerophosphate to glycerol and PO₄^-3.
E) ?-glycerophosphate to choline phosphate.

Question 22

Levels of this enzyme are useful in the diagnosis of a genetic defect, which leads to increased apnea (difficulty breathing) after surgery using succinyl choline.

A) Cholinesterase
B) Aldolase
C) Leucine aminopeptidase
D) 5' nucleotidase
E) Acid phosphatase