Question banks for 1st midterm Flashcards
1
Q
Which amino acid is an activator of N-acetyl-glutamate synthase?
Select one:
A. Glutamine
B. Lysine
C. Arginine
D. Aspartate
E. Asparagine
A
C. Arginine
2
Q
In what form is ammonia transported from muscle to the liver?
Select one:
A. Asparagine
B. Arginine
C. Leucine
D. Glutamine
E. Valine
A
D. glutamine
3
Q
Which hepatocytes express the highest activity of the ornithine cycle enzymes?
Select one:
A. Periportal
B. Pericentral
C. Perivenous
D. Centrolobular
A
B. pericentral
4
Q
Which amino acid contributes to the increase in the activity of the sirtuins?
Select one:
A. Tryptophan
B. Phenylalanine
C. Tyrosine
D. Valine
E. Glutamine
A
A. Tryptophan
(it can be used to generate NAD+)
5
Q
What is the effect of acidosis on the activity of glutamine synthesis in the liver?
Select one:
A. Increase in the periportal hepatocytes
B. Increase in the pericentral hepatocytes
C. Decrease in the perivenous hepatocytes
D. Decrease in all the regions of the lobules
A
B. Increase in the pericentral hepatocytes
6
Q
Which amino acid does NOT contribute to the formation of pyruvate in the course of its degradation?
A. Alanine
B. Glutamine
C. Tyrosine
D. Leucine
E. Aspartate
A
D. Leucine
7
Q
Which amino acid can NOT provide any C-atom for the synthesis of glucose in humans?
Select one:
A. Glutamate
B. Isoleucine
C. Leucine
D. Phenylalanine
E. Tryptophan
A
C. Leucine
8
Q
Which pair of amino acids are released at the highest concentration from skeletal muscle in the fasting state?
Select one:
A. Glutamate, aspartate
B. Glutamine, asparagine
C. Alanine, glutamine
D. Alanine, leucine
E. Valine, leucine
A
C. Alanine, glutamine
9
Q
What happens in the course of glutaminolysis?
Select one:
A. Glutamine is converted to aspartate
B. Glutamine is converted to asparagine
C. Glutamine is completely oxidized to CO2 and water
D. Glutamine is converted to glucose
A
A. Glutamine is converted to aspartate
10
Q
Which amino acid is the most common source of the 1C groups transferred by tetrahydrofolate?
Select one:
A. Alanine
B. Serine
C. Threonine
D. Isoleucine
E. Methionine
A
B. Serine
11
Q
Deficiency of which vitamin would cause enhanced excretion of methylmalonate in the urine?
Select one:
A. B1
B. B2
C. Biotin
D. B12
E. D
A
D. B12
12
Q
Which amino acids should be enriched in the diet of a patient with phenylketonuria?
Select one:
A. Phe, Gln
B. Arg, Lys
C. Trp, Tyr
D. Asp, Glu
E. Ala, Glu
A
C. Trp, Tyr
13
Q
Which interconversion includes glutamic semialdehyde as an intermediate?
A. Arginine to Proline
B. Glutamate to Glutamine
C. Glutamate to a-ketoglutarate
D. Methionine to Threonine
A
A. Arginine to Proline
14
Q
Which vitamin is a co-factor in the synthesis of hydroxyproline?
Select one:
A. B1
B. B2
C. B6
D. B12
E. C
A
E. C
15
Q
What is the role of Se in the function of the thyroid gland?
Select one:
A. Se participates in the structure of thyroxine
B. Se participates in the structure of thyroglobulin
C. Se participates in the structure of deiodinase
D. Se forms a complex with iodine to activate it for thyroxine synthesis
A
C. Se participate in the structure of deiodinase
(Thyroid hormones; T3 - T4)
16
Q
How is the nitrogen balance changed, if the food is depleted of Leu, but all other AA are doubled?
Select one:
A. No change
B. Negative N-balance
C. Positive N-balance
D. Positive N-balance only in children
E. Positive N-balance only in adults
A
B. Negative N-balance
17
Q
How is the nitrogen balance changed, if the food is depleted of Glu, but all other AA are doubled?
Select one:
A. No change
B. Negative N-balance
C. Positive N-balance
D. Negative only in children
E. Positive only in adults
A
A. No change
18
Q
Dietary supplementation with which AA could counteract the sleep-promoting effect of serotonin?
Select one:
A. Glu
B. Trp
C. Leu
D. Lys
E. Arg
A
C. Leu
19
Q
Which one is a metalloprotease?
A. Pepsin
B. Trypsin
C. Elastase
D. Carboxypeptidase
E. Chymotrypsin
A
D. Carboxypeptidase
20
Q
Which zymogen does not need another protease for its activation?
Select one:
A. Trypsinogen
B. Pepsinogen
C. Chymotrypsinogen
D. Proelastase
A
B. Pepsinogen
21
Q
Which AA is present in the active site of the proteasome proteases?
Select one:
A. Aspartate
B. Tyrosine
C. Lysine
D. Threonine
E. Tryptophan
A
D. Threonine
22
Q
Which metal ion is present in the active site of the matrix metalloproteases?
Select one:
A. Zn2+
B. Fe2+
C. Fe3+
D. Cu2+
E. Ca2+
A
A. Zn2+
23
Q
Which AA acts as a signal to suppress autophagy?
Select one:
A. Glycine
B. Leucine
C. Glutamate
D. Glutamine
E. Arginine
A
B. Leucine
24
Q
Which compound is the first N-free intermediate released in the indirect deamination of aspartate?
Select one:
A. Pyruvate
B. Oxaloacetate
C. Fumarate
D. a-ketoglutarate
E. Methylmalonate
A
C. Fumarate
25
Which protein kinase is activated to transmit the anabolic signal of insulin?
Select one:
A. PKA
B. AMPK
C. PKC
D. mTOR
D. mTOR
26
Where is hepcidin produced?
Select one:
A. Liver
B. Spleen
C. Intestine
D. Adrenal gland
E. Pancreas
A. Liver
27
What is the normal degree of transferrin saturation with iron?
Select one:
A. 10%
B. 30%
C. 60%
D. 80%
E. 100-120%
B. 30%
28
Which intermediate is elevated in blood in lead poisoning?
Select one:
A. δ-aminolevulinate
B. Protoporphyrin
C. Haem
D. Bilirubin
E. Biliverdin
A. δ-aminolevulinate
29
Which factor regulates the activity of the aminolevulinate synthase 1 (ALAS1)?
Select one:
A. Ferroportin
B. Transferrin receptor 2
C. Haem
D. Iron response element binding protein 1
E. Ferritin
C. Haem
30
Which factor regulates the activity of aminolevulinate synthase 2 (ALAS2)?
Select one:
A. Protoporphyrin
B. Haemoglobin
C. Haem
D. Iron response element binding protein 1
E. Ferroportin
D. Iron response element binding protein 1
31
Which compound is a substrate of haem oxygenase?
Select one:
A. O2
B. CO
C. CO2
D. HCO3-
A. O2
32
Which compound is a product of haem oxygenase?
Select one:
A. CO
B. O2
C. CO2
D. HCO3-
E. NAPDH
A. CO
33
Why is blue light used to treat neonatal icterus?
Select one:
A. Blue light promotes the conjugation of bilirubin
B. Blue light activates the haem oxygenase in the skin
C. Blue light generates lipid-soluble photoisomers of bilirubin
D. Blue light generates photoisomers of bilirubin with higher water
solubility
D. Blue light generates photoisomers of bilirubin with higher water solubility
34
In what form do the dietary purine bases enter the blood circulation?
Select one:
A. Nucleotide
B. Nucleoside
C. Free base
D. Uric acid
D. Uric acid
35
Which enzyme is needed for the salvage of purine bases?
Select one:
A. Phosphoribosyl-pyrophosphate synthetase
B. Xanthine oxidase
C. Xanthine dehydrogenase
D. AMP deaminase
A. Phosphoribosyl- pyrophosphate synthetase
36
Which two amino acids contribute with 2 N atoms each to the de novo synthesis of one adenine?
Select one:
A. Asparagine, Glutamine
B. Aspartate, Glutamine
C. Asparagine, Glutamate
D. Aspartate, Glutamate
B. Aspartate, Glutamine
37
Which amino acid contributes with both C and N atoms to the de novo syntheses of adenine?
Select one:
A. Glycine
B. Glutamine
C. Aspartate
D. Tryptophan
A. Glycine
38
The degradation of which nucleotide generates propionyl-CoA?
Select one:
A. AMP
B. GMP
C. UMP
D. TMP
D. TMP
39
Which amino acid contributes with 4 atoms to the de-novo synthesis of one pyrimidine ring?
Select one:
A. Glycine
B. Proline
C. Aspartate
D. Proline
C. Aspartate
40
Which compound is a substrate of the ribonucleotide reductase?
Select 1:
A. AMP
B. ADP
C. ATP
D. Phosphoribosyl-pyrophosphate
B. ADP
41
Identify the following amino acid
Glycine
42
Identify the following amino acid
Aspartic acid
43
Identify the following amino acid:
Asparagine
44
Identify the following amino acid:
Glutamic acid
45
Identify the following amino acid:
Glutamine
46
Identify the following amino acid:
Arginine
47
Identify the following amino acid:
Lysine
48
Identify the following amino acid:
Histidine
49
Identify the following amino acid:
Phenylalanine
50
Identify the following amino acid:
Tyrosine
51
Identify the following amino acid:
Tryptophan
52
Identify the following amino acid:
Glycine
53
Identify the following amino acid:
Proline
54
Identify the following amino acid:
Valine
55
Identify the following amino acid:
Leucine
56
Identify the following amino acid:
Isoleucine
57
Identify the following amino acid:
Serine
58
Identify the following amino acid:
Threonine
59
Identify the following amino acid:
Cysteine
60
Identify the following amino acid:
Methionine
61
Select all the valid statements (one or more)
A. In the course of the urea cycle fumarate is produced
B. Enzymes of the urea cycle participate in the de novo synthesis of arginine
C. The amide group of glutamine serves as nitrogen source for the N-
acetylglutamate-activated carbamoylphosphate synthetase
D. Ornithine can be synthesized from glutamate
A. In the course of the urea cycle fumarate is produced
B. Enzymes of the urea cycle participate in the de novo synthesis of arginine
D. Ornithine can be synthesized from glutamate
62
Select all the valid statements (one or more)
A. Citrullin is an intermediate of the urea cycle
B. Citrullin is a precursor of the de novo arginine biosynthesis
C. Urea may be produced by the kidney
D. Arginine may be produced by the kidney
A. Citrullin is an intermediate of the urea cycle
B. Citrullin is a precursor of the de novo arginine biosynthesis
D. Arginine may be produced by the kidney
63
Select the false statement
Select one:
A. Urea can be produced by the kidney
B. The nitrogen atoms present in urea are derived from free ammonium
ion and from aspartate
C. The de novo synthesis of arginine requires ornithine synthesis
D. Ornithine is synthesized from glutamate
E. Arginine may be produced in the kidney
A. Urea can be produced by the kidney
64
A part of the carbon skeleton of which amino acids may enter the citric acid cycle in the form of succinyl-CoA?
Select one or more:
A. Isoleucine
B. Leucine
C. Tyrosine
D. Proline
E. Valine
A. Isoleucine
E. Valine
65
A part of the carbon skeleton of which amino acids may enter the citric acid cycle in the form of a-ketoglutarate?
Select one or more:
A. Proline
B. Glutamine
C. Arginine
D. Cysteine
E. Phenylalanine
A. Proline
B. Glutamine
C. Arginin
66
A part of the carbon skeleton of which amino acids may enter the citric acid cycle?
Select one or more:
A. Leucine
B. Asparagine
C. Phenylalanine
D. Tyrosine
B. Asparagine
C. Phenylalanine
D. Tyrosine
67
Which of the following answer(s) complete(s) the sentence correctly?
Glutamate is reduced to glutamic semialdehyde in the course of the formation of...
Select one or more:
A. Ornithine
B. Proline
C. Glutamine
D. Glutathione
E. G-aminobutyrate
A. Ornithine
B. Proline
68
Select all valid statements (one or more):
A. Formation of tyrosine is an essential step in the physiological degradation of phenylalanine
B. Degradation of phenylalanine starts with removal of the amino group by phenylalanine a-ketoglutarate transaminase
C. The carbon skeleton of phenylalanine yields acetoacetate
A. Formation of tyrosine is an essential step in the physiological degradation of phenylalanine
C. The carbon skeleton of phenylalanine yields acetoacetate
69
Select all valid statements (one or more):
A. Formation of tyrosine is an essential step in the physiological degradation of phenylalanine
B. Phenylalanine may lose its amino group by a phenylalanine a- ketoglutarate transaminase under pathological conditions
C. Carbon skeleton of phenylalanine yields acetoacetate
A. Formation of tyrosine is an essential step in the physiological degradation of phenylalanine
B. Phenylalanine may lose its amino group by a phenylalanine a- ketoglutarate transaminase under pathological conditions
C. Carbon skeleton of phenylalanine yields acetoacetate
70
Select all the valid statements (one or more):
A. Folic acid should be reduced in order to serve as a one carbon carrier
B. S-adenosylmethionine is a methyl-group donor
C. Regeneration of S-adenosylmethionine from S-adenosylhomocysteine requires B12 vitamin
D. One carbon unit carried by the derivative of folic acid are derived from S-adenosylmethionine
A. Folic acid should be reduced in order to serve as a one carbon carrier
B. S-adenosylmethionine is a methyl-group donor
C. Regeneration of S-adenosylmethionine from S-adenosylhomocysteine requires B12 vitamin
71
Select all valid statements (one or more):
A. One carbon unit carried by tetrahydrofolic acid may be derived from serine, glycine, tryptophan or histidine
B. All one carbon units bound by tetrahydrofolic acid can be transformed into each other
C. The methyl group carried by tetrahydrofolic acid is derived from methionine
One carbon unit carried by tetrahydrofolic acid may be derived from serine, glycine, tryptophan or histidine
(is more versatile than the other cofactors in that it functions to transfer C1 units
in several oxidation states.)
72
Which of the following amino acid are nutritionally essential for the human organism?
Select one or more:
A. Proline
B. Valine
C. Phenylalanine
D. Methionine
E. Cysteine
B. Valine
C. Phenylalanine
D. Methionine
73
Which of the following amino acids are nutritionally non-essential for the human organism?
Select one or more:
A. Proline
B. Valine
C. Tyrosine
D. Methionine
E. Cysteine
A. Proline
C. Tyrosine
E. Cysteine
74
Which of the following amino acids are nutritionally essential for the human organism?
Select one or more:
A. Isoleucine
B. Serine
C. Cysteine
D. Phenylalanine
E. Tryptophan
A. Isoleucine
D. Phenylalanine
E. Tryptophan
75
Select the enzymes which can directly catalyze the release of ammonia
Select one or more:
A. Glutaminase
B. Glutamate dehydrogenase
C. Isoleucine-a-ketoglutarate aminotransferase
D. Arginase
E. Mitochondrial carbamoylphosphate synthetase
A. Glutaminase
B. Glutamate dehydrogenase
76
Select those enzymes which can incorporate free ammonia (from ammonium ion) into organic compounds!
Select one or more:
a. Glutamine synthetase
b. Glutamate dehydrogenase
c. Mitochondrial carbamoylphosphate synthetase
d. Arginosuccinate lyase
e. Asparagine synthetase
a. Glutamine synthetase
b. Glutamate dehydrogenase
c. Mitochondrial carbamoylphosphate synthetase
77
Select the false statement!
Select one:
a. Aspartate is a nitrogen donor in the course of urea formation
b. One of the nitrogen atoms of urea is derived from free ammonia
c. The amide group of glutamines is removed by glutamate dehydrogenase
d. The amino group of alanine may be released as free ammonia in a series of two consecutive reactions
e. The transaminase reactions require pyridoxal phosphate
c. The amide group of glutamines is removed by glutamate dehydrogenase
78
Which of the following reactions, enzymes or compounds participate in the urea cycle?
Select one or more:
a. synthesis of carbamoyl phosphate
b. aspartate
c. formation of argininosuccinate
d. ornithine
e. arginase
a. synthesis of carbamoyl phosphate
b. aspartate
c. formation of argininosuccinate
d. ornithine
e. arginase
79
Phenylketonuria can be a consequence of
Select one or more:
a. dihydrobiopterin reductase deficiency
b. vitamin B6 deficiency
c. phenylalanine hydroxylase deficiency
d. defective synthesis of biopterin
e. vitamin C deficiency
a. dihydrobiopterin reductase deficiency
c. phenylalanine hydroxylase deficiency
d. defective synthesis of biopterin
80
Which of the urea cycle enzymes are not localized in the cytosol?
Select one or more:
a. carbamoyl phosphate synthetase I
b. ornithine transcarbamoylase
c. argininosuccinate lyase
d. argininosuccinate synthetase
e. arginase
a. carbamoyl phosphate synthetase I
b. ornithine transcarbamoylase
81
What is the fate of the exocytosed glutamic acid localized in the synaptic cleft?
Select one or more:
a. Glutamate can enter into the postsynaptic neuron by ionotropic receptors
b. Glutamate dehydrogenase splits the molecule in the synaptic cleft, the formed alfa-ketoglutarate is taken up by the postsynaptic neuron
c. Most of glutamate is taken up by astrocytes at the expense of Na+ gradient.
d. Glutamate is transformed into glutamine in astrocytes
e. Released glutamate will be recycled to the neurons in the form of glutamine
c. Most of glutamate is taken up by astrocytes at the expense of Na+ gradient.
d. Glutamate is transformed into glutamine in astrocytes
e. Released glutamate will be recycled to the neurons in the form of glutamine
82
Which of the following statements is/are true for the digestive enzymes?
Select one or more:
a. The carboxypeptidase is a carboxyl protease
b. Elastase and pepsin are thiol proteases
c. No Zn2+ protease can be found in the gastrointestinal tract
d. Both trypsin and chymotrypsin are serine proteases.
d. Both trypsin and chymotrypsin are serine proteases.
83
Which of the following agents and enzymes are required for the synthesis of cysteine?
Select one or more:
a. methionine
b. adenosyl homocysteinase
c. serine
d. cystathionine synthase
e. cystathionase
a. methionine
b. adenosyl homocysteinase
c. serine
d. cystathionine synthase
e. cystathionase
84
Which of the following statements are valid for transamination?
Select one or more:
a. It is a reversible reaction
b. The coenzyme of transaminases is a noncovalently bound cobalamin
c. In the first step of catalysis ketoacids are attached to the lysine residue of the enzyme forming a Schiff base
d. The Schiff base linkage is in tautomeric equilibrium between an aldimine and a ketamine.
a. It is a reversible reaction
d. The Schiff base linkage is in tautomeric equilibrium between an aldimine and a ketamine.
85
Tetrahydrofolate has the following one-carbon derivatives:
Select one or more:
a. methyl H4folate
b. methylene H4folate
c. methenyl H4folate
d. carboxyl H4folate
a. methyl H4folate
b. methylene H4folate
c. methenyl H4folate
86
S Adenosylmethionine (SAM) is the methyl donor in the synthesis of
Select one or more:
a. carnitine
b. epinephrine
c. choline
d. norepinephrine
a. carnitine
b. epinephrine
c. choline
87
S Adenosylmethionine (SAM) is the methyl donor in the synthesis of
Select one or more:
a. urea
b. methyl-malonyl-CoA
c. choline
d. epinephrine
c. choline
d. epinephrine
88
Transamination of the following amino acids results in formation of citric acid cycle intermediates
Select one or more:
a. lysine
b. aspartate
c. leucine
d. glutamate
b. aspartate
d. glutamate
89
Degradation of the following amino acids results in formation of citric acid cycle intermediates
Select one or more:
a. valine
b. leucine
c. isoleucine
d. tryptophane
a. valine
c. isoleucine
90
Which of the following amino acids are ketoplastic?
Select one or more:
a. serine
b. leucine
c. Cysteine
d. lysine
b. leucine
d. lysine
(A ketogenic amino acid is an amino acid that can be degraded directly into acetyl-CoA)
91
The reaction catalysed by the mitochondrial carbamoyl phosphate synthetase
Select one or more:
a. uses 2 ATP molecules
b. uses glutamine as a substrate
c. inhibited by N-acetylglutamate
d. activated by N-acetylglutamate
a. uses 2 ATP molecules
d. activated by N- acetylglutamate
92
Which of the following statements are true for the urea cycle?
Select one or more:
a. A citric acid cycle intermediate is formed in the cycle
b. The enzymes of the cycle are located either in the cytosol or in the mitochondria
c. Condensation of citrulline and glutamate requires hydrolysis of ATP
d. Synthesis of one urea molecule consumes energy equivalent to three high group transfer potential bonds
a. A citric acid cycle intermediate is formed in the cycle
b. The enzymes of the cycle are located either in the cytosol or in the mitochondria
93
Synthesis of tyrosine requires
Select one or more:
a. dietary phenylalanine
b. phenylalanine hydroxylase
c. tetrahydrobiopterin
d. dihydrobiopteridine reductase
e. transamination of phenylalanine
a. dietary phenylalanine
b. phenylalanine hydroxylase
c. tetrahydrobiopterin
d. dihydrobiopteridine reductase
94
Synthesis of proline involves
Select one or more:
a. glutamate
b. N-methyl-lysine
c. pyrroline-5-carboxylate reductase
d. glutamic semialdehyde
e. pyrroline-5-carboxylate
a. glutamate
b. N-methyl-lysine
c. pyrroline-5-carboxylate reductase
d. glutamic semialdehyde
e. pyrroline-5-carboxylate
(The initial reaction of proline biosynthesis converts the γ-carboxyl group of glutamate to the mixed acid anhydride of glutamate γ-phosphate (Figure 27-3). Subsequent reduction forms glutamate γ-semialdehyde, which following spontaneous cyclization is reduced to l-proline (Figure 27–10).)
95
Tryptophan can be the precursor of the following compounds:
Select one or more:
a. Lysine
b. acetoacetyl-CoA
c. nicotinamide
d. alanine
e. serotonin
b. acetoacetyl-CoA
c. nicotinamide
d. alanine
e. serotonin
96
Which of the following enzymes are regulated by N-acetylglutamate?
Select one:
a. N-acetylglutamate synthase
b. Ornithine transcarbamoylase
c. Carbamoyl phosphate synthetase I
d. Carbamoyl phosphate synthetase II
e. Arginase
c. Carbamoyl phosphate synthetase I
97
Which of the following parameters are suitable to differentiate the deficiency of carbamoyl phosphate synthetase I and ornithine transcarbamoylase?
Select one:
a. Determination of blood pH
b. Determination of citrulline level in blood
c. Determination of arginine level in plasma
d. Determination of orotic acid level in urine
e. Determination of ammonia level in blood
d. Determination of orotic acid level in urine
98
Patients with deficiency of carbamoyl phosphate synthetase I and ornithine transcarbamoylase are treated with sodium benzoate and sodium phenylacetate. What is the rationale of this treatment?
Select one or more:
a. Benzoate conjugates with Gly and removes 1 N atom
b. Phenylacetate conjugates with Hippurate and removes 1 N atom
c. Benzoate and phenylacetate activate the enzymes of urea cycle
d. Phenylacetate conjugates with glutamine and removes 2 N atoms
e. N- containing conjugation products of benzoate and phenylacetate are released in the urine
a. Benzoate conjugates with Gly and removes 1 N atom
b. Phenylacetate conjugates with Hippurate and removes 1 N atom
e. N- containing conjugation products of benzoate and phenylacetate are released in the urine
99
Which of the following intermediates can be converted to serine in a single step reaction?
Select one:
a. Pyruvate
b. Some citric acid cycle intermediates
c. Some ornithine cycle intermediates
d. Glycine
e. Choline
d. Glycine
100
Which of the following amino acids are non-essential for an adult human?
Select one or more:
a. Phe
b. Tyr
c. Met
d. Cys
e. Glu
b. Tyr
d. Cys
e. Glu
101
Which of the following proteases is/are involved in the activation of pancreatic proenzymes?
Select one or more:
a. Carboxypeptidase A
b. Enteropeptidase
c. Trypsin
d. Chymotrypsin
e. Elastase
b. Enteropeptidase
c. Trypsin
102
Which of the following statements are valid for aminotransferases (AT)? The AT needs:
Select one or more:
a. Efficient amount of Vitamin B6
b. The presence of free amino acids
c. The presence of free ketoacids
d. The formation of Schiff base between the amino group of the amino acid and aldehyde group of pyridoxal phosphate
e. The presence of AT in blood circulation
a. Efficient amount of Vitamin B6
b. The presence of free amino acids
c. The presence of free ketoacids
d. The formation of Schiff base between the amino group of the amino acid and aldehyde group of pyridoxal phosphate
103
Which of the following statements are valid for the S-adenosylmethionine cycle?
Select one or more:
a. Met + ATP forms S-adenosylmethionine
b. Stable covalent bond exists between one C atom of Met and 5'C atom of adenosine
c. S-adenosylmethionine is converted to homocysteine + H2O
d. Homocysteine+ N5-Methyl FH4 form Met + FH4
e. Homocysteine methyltransferase uses a vitamin B12 derived cofactor
a. Met + ATP forms S- adenosylmethionine
d. Homocysteine+ N5-Methyl FH4 form Met + FH4
e. Homocysteine methyltransferase uses a vitamin B12 derived cofactor
104
Which of the following amino acids have their alpha-amino groups removed by dehydratases?
Select one or more:
a. Histidine
b. Tryptophan
c. Serine
d. Glutamine
e. Threonine
c. Serine
e. Threonine
105
Which of the following amino acids are derived from alpha-ketoglutarate?
Select one or more:
a. Glutamate
b. Cysteine
c. Aspartate
d. Proline
e. Serine
a. Glutamate
d. Proline
106
Which of the following statements are valid for N-acetyl-glutamate?
Select one or more:
a. its concentration depends on the concentration of arginine
b. its concentration depends on the concentration of ornithine
c. it is an activator of carbamoyl phosphate synthetase I
d. it is an inhibitor of argininosuccinate lyase
e. it is an activator of ornithine transcarbamoylase
a. its concentration depends on the concentration of arginine
c. it is an activator of carbamoyl phosphate synthetase I
107
Hyperhomocysteinemia can be the consequence of:
Select one or more:
a. cystathionine -synthase deficiency
b. methylene tetrahydrofolate reductase deficiency
c. folate deficiency
d. B12 deficiency
e. methionine deficiency
a. cystathionine -synthase deficiency
b. methylene tetrahydrofolate reductase deficiency
c. folate deficiency
d. B12 deficiency
108
High citrulline levels are characteristic in the following enzyme deficiencies:
Select one or more:
a. carbamoyl phosphate synthetase
b. arginino succinate synthetase
c. arginino succinase
d. ornithine transcarbamoylase
b. arginino succinate synthetase
c. arginino succinase
109
Which enzyme is critical in the activation of zymogens for the digestion of proteins in the small intestine?
Select one:
a. enteropeptidase
b. hexokinase
c. papain
d. pepsin
e. secretin
a. enteropeptidase
110
Which of these is NOT an intestinal protease?
Select one:
a. chymotrypsin
b. elastase
c. enteropeptidase
d. pepsin
e. trypsin
d. pepsin
111
Which of the following is a zymogen that can be converted to an endopeptidase that hydrolyses peptide bonds adjacent to Lys and Arg residues?
Select one:
a. Chymotrypsinogen
b. pepsin
c. pepsinogen
d. Proelastase
e. trypsinogen
e. trypsinogen
112
In amino acid catabolism, the first reaction for many amino acids is a:
Select one:
a. decarboxylation requiring thiamine pyrophosphate (TPP). b. hydroxylation requiring NADPH and O2.
c. oxidative deamination requiring NAD+.
d. reduction requiring pyridoxal phosphate (PLP).
e. transamination requiring pyridoxal phosphate.
e. transamination requiring pyridoxal phosphate.
113
The cofactor required for all transaminations is derived from:
Select one:
a. niacin.
b. pyridoxine (vitamin B6).
c. riboflavin
d. thiamine.
e. vitamin B12
b. pyridoxine (vitamin B6).
114
The cofactor involved in a transaminase reaction is:
Select one:
a. biotin phosphate.
b. lipoic acid.
c. nicotinamide adenine dinucleotide phosphate (NADP+). d. pyridoxal phosphate (PLP)
e. thiamine pyrophosphate (TPP).
d. pyridoxal phosphate (PLP)
115
Transamination of alanine to alpha-ketoglutarate requires the cofactor:
Select one:
a. thiamine pyrophosphate (TPP).
b. pyridoxal phosphate (PLP).
c. No coenzyme is involved.
d. NADH.
e. biotin.
b. pyridoxal phosphate (PLP).
116
Pyridoxal phosphate is a cofactor in this class of reactions:
Select one:
a. transamination.
b. reduction.
c. methylation.
d. desulfuration.
e. acetylation.
a. transamination.
117
Which of the following is not true for the reaction catalyzed by glutamate dehydrogenase?
Select one:
a. The reaction is similar to transamination in that it involves the coenzyme pyridoxal phosphate (PLP).
b. The enzyme is specific for glutamate.
c. The enzyme can use either NAD+ or NADP+ as a cofactor.
d. NH4+ is produced.
e. alpha-ketoglutarate is produced
a. The reaction is similar to transamination in that it involves the coenzyme pyridoxal phosphate (PLP).
118
Glutamate is metabolically converted to alpha-ketoglutarate and NH4+ by a process described as:
Select one:
a. transamination.
b. reductive deamination.
c. hydrolysis.
d. deamidation
e. oxidative deamination
e. oxidative deamination
119
The conversion of glutamate to an alpha-ketoacid and NH4+:
Select one:
a. does not require any cofactors.
b. is a reductive deamination.
c. is accompanied by ATP hydrolysis catalyzed by the same enzyme.
d. is catalyzed by glutamate dehydrogenase.
e. requires ATP.
d. is catalyzed by glutamate dehydrogenase.
120
Which substance is NOT involved in the production of urea from NH4+ via the urea cycle?
Select one:
a. ornithine
b. malate
c. carbamoyl phosphate
d. ATP
e. aspartate
b. malate
121
A nitrogen atom of which compound is incorporated in the urea by an enzyme of the urea cycle?
Select one:
a. ornithine
b. glutamate
c. carnitine
d. aspartate
e. adenine
d. aspartate
122
Conversion of ornithine to citrulline is a step in the synthesis of:
Select one:
a. urea.
b. tyrosine.
c. pyruvate.
d. carnitine.
e. aspartate.
a. urea
123
In the urea cycle, ornithine transcarbamoylase catalyzes:
Select one:
a. cleavage of urea to ammonia.
b. formation of citrulline from ornithine and another reactant.
c. formation of ornithine from citrulline and another reactant.
d. formation of urea from arginine.
e. transamination of arginine
b. formation of citrulline from ornithine and another reactant.
124
The amino acids serine, alanine, and cysteine can be catabolized to yield:
Select one:
a. succinate.
b. pyruvate.
c. oxaloacetate
d. fumarate.
e. alpha-ketoglutarate.
b. pyruvate.
125
Serine or cysteine may enter the citric acid cycle as acetyl-CoA after conversion to:
Select one:
a. oxaloacetate.
b. propionate.
c. pyruvate.
d. succinate.
e. succinyl-CoA.
c. pyruvate.
126
The human genetic disease phenylketonuria (PKU) can result from:
Select one:
a. inability to convert phenylalanine to tyrosine.
b. deficiency of protein in the diet.
c. inability to catabolize ketone bodies.
d. inability to synthesize phenylalanine.
e. production of enzymes containing no phenylalanine.
a. inability to convert phenylalanine to tyrosine.
127
Nonessential amino acids:
Select one:
a. may be substituted with other amino acids in proteins.
b. can be synthesized in humans.
c. are synthesized by plants and bacteria, but not by humans.
d. are not utilized in mammalian proteins.
e. cannot be converted to intermediates of the citric acid cycle.
b. can be synthesized in humans.
128
Glutamine, arginine, and proline:
Select one:
a. do not have a common precursor in their synthesis
b. may all be derived from a citric acid cycle intermediate.
c. may all be derived from a glycolytic intermediate.
d. may all be derived from a urea cycle intermediate.
b. may all be derived from a citric acid cycle intermediate.
129
Delta-aminolaevulinic acid is formed from succinyl-CoA and __________ and is an intermediate in the biosynthesis of _________.
Select one:
a. serine; sphingosine
b. serine; heme
c. acetyl-CoA; long chain fatty acids
d. alpha-ketoglutarate; glutamate and proline
e. glycine; porphyrin
e. glycine; porphyrin
130
Glutathione is a:
Select one:
a. product of glutamate and methionine.
b. tripeptide of glycine, glutamate, and cysteine.
c. enzyme essential in the synthesis of glutamate.
d. methyl-group donor in many biosynthetic pathways.
b. tripeptide of glycine, glutamate, and cysteine.
131
Which amino acid is not directly involved in the purine biosynthetic pathway?
Select one:
a. alanine.
b. aspartate.
c. glutamine.
d. glycine.
a. alanine.
132
Which of the amino acids below have a small polar side chain containing a hydroxyl group?
Select one or more:
a. Glycine
b. Serine
c. Threonine
d. Lysine
e. Leucine
c. Threonine
