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Essential Biochemistry - Protein Metabolism (Section 4)

1
Which of the following is a key function of histidine?
Answer
(B)
Precursor for histamine synthesis
2
What is the role of Carboxypeptidase?
Answer
(B)
Removes amino acids from the C-terminal end of a peptide.
3
Which amino acids are both ketogenic and glucogenic?
Answer
A
C
D
4
Norepinephrine is converted to epinephrine by:
Answer
(B)
Transmethylation
5
Histidine is converted to histamine by:
Answer
(B)
Decarboxylation
6
Which of the following are causes of high blood urea nitrogen (BUN)?
Answer
A
B
C
7
What is the role of tetrahydrobiopterin in the conversion of phenylalanine to tyrosine?
Answer
(A)
It is a coenzyme
8
What is the main goal of amino acid catabolism?
Answer
(B)
To generate energy.
9
Where does most protein digestion occur?
Answer
(C)
Jejunum
10
What is the primary function of the enzyme aspartyl transaminase?
Answer
(B)
Transferring the amino group of aspartate to an alpha-keto acid
11
What is the role of glutamate dehydrogenase?
Answer
(B)
To remove the amino group from glutamate.
12
The first step in the degradation of branched-chain amino acids is:
Answer
(A)
Transamination
13
Which of the following amino acids can be converted to glutamate?
Answer
A
B
C
D
14
What is the role of ammonia in the body?
Answer
A
B
D
15
Which amino acid is a precursor for the synthesis of urea?
Answer
(B)
Arginine
16
What is the role of Carbamoyl Phosphate Synthetase I (CPS I) in the urea cycle?
Answer
(A)
To convert ammonia and CO2 to carbamoyl phosphate.
17
Where does the first step of urea cycle occur?
Answer
(B)
Mitochondria
18
Which organ is most affected by hyperammonemia?
Answer
(C)
Brain
19
Which vitamin is required for the activity of methylenetetrahydrofolate reductase?
Answer
(C)
Vitamin B9
20
What is a characteristic of a person in nitrogen equilibrium?
Answer
(C)
Nitrogen intake is equal to nitrogen excretion.
21
Which enzyme is deficient in the disease known as homocystinuria?
Answer
(A)
Cystathionine β-synthase
22
Which of the following amino acids contributes to the synthesis of epinephrine?
Answer
(B)
Tyrosine
23
Which of the following is the primary site of catabolism for amino acids?
Answer
(A)
Liver
24
Which amino acids are directly involved in the formation of the tripeptide glutathione?
Answer
(B)
Cysteine, glycine, glutamate
25
What is the primary function of melanin?
Answer
(A)
Protecting skin from UV damage
26
Which of the following is NOT directly synthesized from tryptophan?
Answer
(D)
Dopamine
27
Which of the following pathways occurs in part in the mitochondria and in part in the cytoplasm?
Answer
(A)
Urea cycle
28
Which of the following amino acid cannot undergo transamination?
Answer
(A)
Lysine
29
All of the following are intermediates formed by amino acid degradation, except:
Answer
(D)
Citrate
30
Which of the following amino acids can be converted to form formiminoglutamate?
Answer
(A)
Histidine
31
What is the main product of protein digestion in the intestine that are absorbed?
Answer
(D)
All of the above
32
What are the end products of urea cycle?
Answer
A
B
33
What are the potential consequences of hyperammonemia?
Answer
A
B
C
D
34
Which of the following amino acid is involved in the synthesis of carnitine?
Answer
(A)
Lysine
35
What is the role of PLP in transamination?
Answer
(C)
It is a coenzyme that accepts and donates the amino group.
36
What is the normal blood urea nitrogen (BUN) range for a healthy adult?
Answer
(A)
10-20 mg/dL
37
Which of the following is a precursor for the synthesis of creatine?
Answer
A
B
C
38
Which pathway is used for the degradation of tryptophan?
Answer
(A)
Kynurenine pathway
39
Where does the urea cycle primarily occur?
Answer
(A)
Liver
40
Which of the following is NOT a product of histidine degradation?
Answer
(B)
Glutamate
41
Which enzyme deficiency leads to albinism?
Answer
(B)
Tyrosinase
42
What is the role of S-adenosylmethionine (SAM) in amino acid metabolism?
Answer
A
B
43
Which of the following is NOT a function of serotonin?
Answer
(D)
Facilitating muscle contraction
44
What is the role of fumarate in the urea cycle?
Answer
(C)
It connects the urea cycle to the citric acid cycle.
45
Carboxypeptidase contains which of the following mineral?
Answer
(D)
Zn
46
Which of the following is the main product of the urea cycle?
Answer
(C)
Urea
47
Which of the following are important in the formation of urea?
Answer
A
B
D
48
Which enzyme activates trypsinogen?
Answer
(B)
Enteropeptidase
49
What is the role of urea cycle in protein metabolism?
Answer
(A)
To convert ammonia into urea for excretion.
50
Which of the following enzyme is secreted by mucosal cell?
Answer
(C)
Aminopeptidase