This set of Biochemistry Multiple Choice Questions & Answers (MCQs) focuses on “Metabolic Fates of Amino Groups”.
1. Glutamate is metabolically converted to α-ketoglutarate and NH4+ by a process ___________
a) Oxidative deamination
b) Transamination
c) Reductive deamination
d) Deamination
View Answer
Explanation: Glutamate is metabolically converted to α-ketoglutarate and NH4+ by a process oxidative deamination catalyzed by L-glutamate dehydrogenase.
2. Free ammonia combined with glutamate to yield glutamine by the action of ___________
a) Glutaminase
b) Glutamine synthase
c) Glutamate dehydrogenase
d) Amino transferase
View Answer
Explanation: The free ammonia is combined with glutamate to yield glutamine by the action of glutamine synthase.
3. Pyridoxal phosphate and its aminate form, pyridoxamine phosphate are tightly bound coenzymes of ___________
a) Amino transferases
b) Glutaminase
c) Glutamine synthase
d) Glutamate dehydrogenase
View Answer
Explanation: All aminotransferases have pyridoxal phosphate (PLP) as cofactor.
4. What is the necessary coenzyme for transamination reactions?
a) Pyridoxal phosphate
b) Thiamine pyrophosphate
c) NAD
d) Coenzyme A
View Answer
Explanation: Pyridoxal phosphate functions as an intermediate carrier of amino groups at the active site of amino transferases.
5. Which is the first step in the catabolism of most L-amino acids once they have reached the liver is promoted?
a) Amino transferases
b) Glutaminase
c) Glutamine synthase
d) Glutamate dehydrogenase
View Answer
Explanation: The first step in the catabolism of most L-amino acids once they have reached the liver is removal of the α-amino groups promoted by enzymes called amino transferases or trasaminases.
6. The combined action of aminotransferase and glutamate dehydrogenase is referred as ___________
a) Oxidative deamination
b) Transamination
c) Reductive deamination
d) Transdeamination
View Answer
Explanation: The combined action of aminotransferase and glutamate dehydrogenase is referred as transdeamination.
7. Glutamine is converted to glutamate and NH4+ by ___________
a) Amino transferases
b) Glutaminase
c) Glutamine synthase
d) Glutamate dehydrogenase
View Answer
Explanation: In the tissues of intestine, liver and kidneys, the amide nitrogen is released as ammonium ion in the mitochondria, where glutaminase converts glutamine to glutamate and NH4+.
8. Which of the following operates at an important intersection of carbon and nitrogen metabolism?
a) Amino transferases
b) Glutaminase
c) Glutamine synthase
d) Glutamate dehydrogenase
View Answer
Explanation: Glutamate dehydrogenase operates at an important intersection of carbon and nitrogen metabolism.
9. Trypsinogen is converted to its active state by ___________
a) Enteropeptidase
b) Glutaminase
c) Glutamine synthase
d) Glutamate dehydrogenase
View Answer
Explanation: Trypsinogen is converted to its active state by enteropeptidase, a proteolytic enzyme secreted by intestinal cells.
10. Which of the following hydrolyzes successive amino-terminal residues from short peptides?
a) Aminopeptidase
b) Enteropeptidase
c) Glutamine synthase
d) Glutamate dehydrogenase
View Answer
Explanation: Aminopeptidase hydrolyzes successive amino-terminal residues from short peptides.
Sanfoundry Global Education & Learning Series – Biochemistry.
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