This set of Enzyme Technology Multiple Choice Questions & Answers (MCQs) focuses on “Clinical Significance of 5′ – Nucleotidase and Acetylcholine Esterase”.
1. Which of the following reaction is not catalyzed by 5I – nucleotidase?
a) Adenosine monophosphate to adenosine
b) Inosine 5I – phosphate to inosine
c) Guanosine monophosphate to guanine
d) Creatine phosphate to creatine
View Answer
Explanation: Creatine phosphate to creatine is catalyzed by creatine kinase which donates the phosphate group to ADP forming ATP. Purine nucleotides are degraded by a pathway in which they lose the phosphate group by action of 5I – nucleotidase in the following ways:
• Adenosine monophosphate to adenosine.
• Inosine 5I – phosphate to inosine.
• Guanosine monophosphate to guanine.
These 3 pathways final product is uric acid.
2. Most of the dietary purines are converted to ________ in the intestinal cells.
a) chymotrypsin
b) creatine
c) uric acid
d) maltase
View Answer
Explanation: Most of the dietary purines are converted to uric acid in the intestinal cells. Chymotrypsinogen is converted to chymotrypsin by trypsin. Creatine is formed from creatine phosphate by donating the phosphate group to ADP to form ATP in presence of creatine kinase. α-amylase hydrolyzes α-1, 4 linkages in starch and glycogen to yield maltase.
3. Excess of uric acid causes ________
a) duodenal ulcer
b) macroamylsemia
c) gout
d) sphincter of oddi
View Answer
Explanation: Excess of uric acid causes gout. In duodenal ulcer, the ampulla is involved in the inflammatory process thus blocking secretion of pancreatic juice into the duodenum. Macroamylasemia results due to increase in plasma amylase with decrease in urinary excretion. Sphincter of oddi results due to contraction of pancreatic duct sphincter.
4. Which of the following statements are not true for gout disease?
a) Blocking secretion of pancreatic juice
b) Disease of joints
c) Joints become inflamed, painful and arthritic
d) Kidneys are also affected
View Answer
Explanation: “Blocking secretion of pancreatic juice.” This statement is not true for gout disease. Following statements are true for gout disease:
• Disease of joints caused by elevated concentration of uric acid in blood.
• Joints become inflamed, painful and arthritic due to the abnormal deposition of uric acid crystals.
• Kidneys are also affected as excess uric acid is deposited in the kidney tubules.
5. Allopurinol is administered to treat gout.
a) True
b) False
View Answer
Explanation: Allopurinol inhibits xanthine oxidase and hence can be administered to treat gout. When xanthine oxidase is inhibited the excreted product of purine metabolism is hypoxanthine, which I more soluble and less likely to from crystalline deposit. Hence the statement is true.
6. Acetylcholinesterase is found in ________
a) saliva juice
b) pancreatic juice
c) matrix of synaptic cleft
d) tears
View Answer
Explanation: Acetylcholinesterase is found in matrix of synaptic cleft. α – amylase is seen in higher concentrations in pancreatic and saliva juice, whereas in lower concentrations in tears.
7. Which enzyme converts acetylcholine to choline and acetate?
a) Acetylcholine esterase
b) Creatine kinase
c) 5I – nucleotidase
d) Transaminase
View Answer
Explanation: Acetylcholine esterase converts acetylcholine to choline and acetate. Creatine kinase converts creatine phosphate to creatine and ATP. Transaminase are the enzymes that are involved in transfer of amino acids. 5I – nucleotidase degrade purine nucleotides by a pathway in which they lose the phosphate group.
8. Which of the following is not a step of action of nerve impulse?
a) Release of acetylcholine
b) Production of the muscle action potential
c) Termination of acetylcholine
d) Guanosine monophosphate to guanine
View Answer
Explanation: “Guanosine monophosphate to guanine.” This is a part of the pathway of purine degradation by 5I – nucleotidase. Steps involved in action of nerve impulse are:
• Release of acetylcholine during exocytosis into the synaptic cleft.
• Activation of acetylcholine receptor by binding of 2 molecules of released acetylcholine which opens the channels of small cations such as Na+.
• Production of muscle action potential due to inflow positively charged sodium ions.
• Termination of acetylcholine by acetylcholine esterase which is attached to collagen fiber in extracellular matrix of synaptic cleft.
9. Which of the following places pseudocholine esterase is not found?
a) Hepatic cells
b) Intestine
c) Pancreatic juice
d) Serum
View Answer
Explanation: α – amylase is seen in higher concentrations in pancreatic and saliva juice. Whereas pseudocholine esterase is found in hepatic cells of liver, intestine and serum.
10. Which of the following is a clinical application of pseudocholine esterase?
a) Acute oliguric renal failure
b) Acute pancreatitis
c) Use for metabolism of certain drugs such as succinyl choline, cocaine
d) Duodenal ulcer
View Answer
Explanation: “Use for metabolism of certain drugs such as succinyl choline, cocaine.” This is a clinical application of pseudocholine esterase. Succinyl choline is a muscle relaxant. If plasma choline esterase concentration is low in serum, then it will cause effect because succinyl choline cannot be metabolized. Following clinical conditions are associated with amylase:
• Acute oliguric renal failure, acute pancreatitis and duodenal ulcer.
11. Which of the following is a clinical application of pseudocholine esterase?
a) Diabetic ketoacidosis
b) Diagnosis of organophosphate poisoning
c) Salivary gland disorders
d) Ruptured ectopic pregnancy
View Answer
Explanation: “Diagnosis of organophosphate poisoning.” This is a clinical application of pseudocholine esterase. Following clinical condition shows an increase of amylase concentration:
• Severe diabetic ketoacidosis.
• Salivary gland disorders such as mumps, salivary calculi.
• Ruptured ectopic pregnancy.
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