Pregunta 1
Pregunta
Which of the following is true?
Respuesta
-
Transaminases are specific for only one pair of α-amino and α-keto acids
-
Transaminases co-work with Vitamin B1 (thiamine pyrophosphate) as coenzyme
-
Transaminases co-work with Vitamin B6 (pyridoxal phosphate) as coenzyme
-
Transaminases fix ammonia as amino group in amino acids
-
Transaminases release free ammonia from α-amino acids
Pregunta 2
Pregunta
Which of the following a-amino acids is essential?
Respuesta
-
Glycine
-
Glutamate
-
Serine
-
Valine
-
Lysine
Pregunta 3
Pregunta
Which of the following α-amino acids are glycogenic?
Respuesta
-
Lysine, Cysteine and Proline
-
Glycine, Alanine and Proline
-
Leucine, lsoleucine and Valine
-
Aspartate, Glutamate and Serine
-
Leucine, Phenylalanine and Tyrosine
Pregunta 4
Pregunta
Which of the following α-amino acids is ketogenic?
Respuesta
-
Glycine
-
Leucine
-
lsoleucine
-
Valine
-
Alanine
Pregunta 5
Pregunta
Which of the following mechanisms play role in ammonia detoxification:
Respuesta
-
Glutamine biosynthesis in brain
-
Urea biosynthesis in muscles
-
Alanine biosynthesis in muscles
-
Urea biosynthesis in liver
-
NH4+ formation in kidney
Pregunta 6
Pregunta
Which of the following statements about glutamate dehydrogenase are true:
Respuesta
-
the enzyme is regulated
-
the enzyme is associated with the respiratory chain and the formation of energy
-
the enzyme uses FAD as cofactor
-
the enzyme uses NAD+ as cofactor
Pregunta 7
Pregunta
Which of the following statements about the urea cycle are true
Respuesta
-
urea catabolizes in urea cycle
-
it does not use cell energy
-
it has mitochondrial and cytosol phase
-
in urea cycle a toxic product is converted into less toxic product which is excreted
Pregunta 8
Pregunta
Which of the following is involved in purine ring formation?
Respuesta
-
Alanine
-
Aspartate
-
Glutamate
-
Carbamoyl phosphate
-
Glycine
Pregunta 9
Pregunta
Which of the following is involved in pyrimidine ring formation?
Respuesta
-
Alanine
-
Aspartate
-
Glutamate
-
Carbamoyl phosphate
-
Glycine
Pregunta 10
Pregunta
Which of the following about GOUT is TRUE:
Respuesta
-
it is characterised by elevated concentration of uric acid in blood
-
it may be due to overproduction of purine nucleotides or decreased renal excretion of uric acid
-
many of the clinical symptoms arise because of the high solubility of uric acid in the aqueous environment
-
allopurinol is used for the treatment of gout since it inhibits xanthine oxidase
Pregunta 11
Pregunta
Which are the end products from pyrimidine degradation
Respuesta
-
uric acid
-
β-aminoisobutyrate
-
urea
-
β-alanine
-
NH3 and CO2
Pregunta 12
Pregunta
Porphyrin biosynthesis occurs in:
Pregunta 13
Pregunta
Which of the following is correct?
Respuesta
-
heme is synthesized from succinyl-CoA and glycine
-
heme is synthesized from aspartate and carbamoyl phosphate
-
heme is an example of iron porphyrins
-
heme is an example of magnesium porphyrins
-
the clinical condition jaundice is due to elevation of bilirubin in blood plasma
Pregunta 14
Pregunta
Which of the following is TRUE:
Respuesta
-
in prehepatic jaundice only the direct bilirubin is increased in serum
-
in hepatic jaundice only the indirect bilirubin is increased in serum
-
in posthepatic (obstructive) jaundice urine urobilinogen is absent
-
the neonatal physiologic jaundice results from an accelerated hemolysis around the time of birth and an immature hepatic system for the uptake, conjugation and excretion of bilirubin
-
Gilbert Syndrome is caused by deficiency in biliverdin reductase
Pregunta 15
Pregunta
Which of the following is true?
Respuesta
-
Carbamoyl phosphate synthetase 1 uses glutamine for the synthesis of urea
-
NH3 may be toxic to the brain because ammonia reacts with α-ketoglutarate to form glutamate and this results in depletion of the levels of α-ketoglutarate which impairs the function of the TCA cycle in neurons
-
clinical symptoms of ammonia intoxication include tremor, slurred speech, blurred vision, coma and ultimately death
-
a high protein diet and starvation result in induction of urea cycle enzymes
Pregunta 16
Pregunta
Which of the following human proteins contain porphyrins:
Respuesta
-
Myoglobin
-
Cyt. P450
-
Cyt. C1
-
Catalase
-
Ferritin
Pregunta 17
Pregunta
Which of the following is NOT TRUE
Respuesta
-
Thymidylate synthase catalyzes the synthesis of dTMP
-
H4 folate derivatives serve as one carbon donor for purine biosynthesis de novo
-
ribonucleotide reductase plays important role in RNA synthesis
-
CTP is produced by amination of UTP by CTP synthetase
Pregunta 18
Pregunta
Which of the following amino acids may undergo oxidative deamination followed by energy production:
Respuesta
-
Glycine
-
Trytophan
-
Lysine
-
Glutamate
-
Cytesine
Pregunta 19
Pregunta
Which of the statements about aminotransferases are TRUE
Respuesta
-
they use thiamine diphosphate as a coenzyme
-
they use pyridoxal phosphate as a coenzyme
-
the ALAT content increases in cardiac infarction
-
the ASAT and ALAT content increases in liver disease (e.g: hepatitis)
Pregunta 20
Pregunta
Which of the following compounds can accept NH2-group in transamination
Respuesta
-
pyruvate
-
acetone
-
α-ketoglutarate
-
acetoacetate
-
oxaloacetate
Pregunta 21
Pregunta
Which of the following biogenicamines are neurotransmitters
Respuesta
-
γ-aminobutyrate (GABA)
-
serotonin
-
tyrosine
-
dopamine
-
adrenaline
Pregunta 22
Pregunta
Which of the following amino acids can not undergo transamination
Respuesta
-
lysine
-
proline
-
alanine
-
glutamate
-
threonine
Pregunta 23
Pregunta
Which of the statements about aminotransferase are TRUE
Respuesta
-
they use NAD + as a coenzyme
-
they use pyridoxal phosphate as a coenzyme
-
the ASAT content increases in cardiac infarction
-
the ASAT and ALAT content decreases in liver disease (e.g hepatitis)
Pregunta 24
Pregunta
Which of the following is TRUE
Respuesta
-
arginine and glycine are used for the biosynthesis of creatine
-
creatine phospate serves a storage form of energy in muscles, heart and brain
-
creatine kinase catalyses the reaction creatine phosphate -> creatinine
-
when ATP is utilized as a source of energy for muscular contraction creatine phosphate maintains its concentration
Pregunta 25
Pregunta
Which of the following compounds are neurotransmitters
Respuesta
-
serine
-
glycine
-
serotonin
-
dopamine
-
acetylcholine
Pregunta 26
Pregunta
Which of the following compounds are amino group acceptors in transaminase reactions?
Respuesta
-
α-ketoglutarate
-
acetone
-
oxaloacetate
-
pyruvate
-
glutamate
Pregunta 27
Pregunta
Which are the end products of N-metabolism?
Respuesta
-
Creatine
-
Creatinine
-
Urea
-
Ammonia
-
Ammonium cations
-
Uric acids
Pregunta 28
Pregunta
Which of the following statements about pyrimidine synthesis are TRUE:
Respuesta
-
Pyrimidine ring is formed by adding atoms to PRPP
-
PRPP is added to the already formed pyrimidine ring
-
Derivatives of tetrahydrofolate (THF) are necessary for TMP production
-
SAM is necessary for TMP production
Pregunta 29
Pregunta
What is the origin of the atoms for "de novo" purine synthesis?
Respuesta
-
N7, C8 and N9 from glycine
-
C4, C5 and N7 from glycine
-
C6 from CO2
-
C8 from CO2
Pregunta 30
Pregunta
Which of the following statements about iron metabolism are FALSE:
Respuesta
-
hemosiderin is the major iron-storage protein
-
ferritin is the major iron-storage protein
-
transrefin can bind only ferrous cations ( Fe3+)
-
transrefin can bind only ferrous cations ( Fe2+)
-
the major regulator of piasma iron concentration is the humoral factor hepcidin
Pregunta 31
Pregunta
Which of the following compounds participate in both Krebs cycle and in transaminase reactions?
Respuesta
-
oxaloacetate
-
acetoacetate
-
α-ketoglutarate
-
pyruvate
-
isocitrate
-
malate
Pregunta 32
Pregunta
N-atom in carbamoyl phosphate, used for pyrimidine ring synthesis, derives from
Respuesta
-
Ammonia (NH3)
-
Aspartate
-
Glutamate
-
Glutamine
-
Glycine
Pregunta 33
Pregunta
Which of the following reactions from urea cycle demand ATP?
Respuesta
-
Arginine -> Ornithine + Urea
-
Ornithine + Carbamoyl phosphate -> Citrulline
-
NH3 + CO2 -> Carbamoyl phosphate
-
Citrulline + Aspartate -> Arginosuccinate
-
Argininosuccinate -> Arginine + Fumarate
Pregunta 34
Pregunta
Which of the following statements about phenylalanine degradation are TRUE?
Respuesta
-
phenylalanine is hydroxylated to tyrosine
-
phenylalanine hydroxylases uses NADPH + H+ as a cofactor
-
a deficiency of homogentisate oxidase cause tyrosinemia type 2
-
a deficiency of phenyalanine hydroxylase results in higher concentration of phenylpyruvate, phenylpyruvate, phenyllactate and phenylacetate
-
phenylalanine hydroxylase uses ascorbic acid as a cofactor
Pregunta 35
Pregunta
Which of the following statements about "de novo“ purine synthesis are TRUE?
Respuesta
-
Purine ring formed by adding atoms to PRPP
-
PRPP to the already formed purine ring
-
Derivatives Of tetrahydrofolate (THF) are necessary for purine synthesis
-
SAM is necessary for purine synthesis
Pregunta 36
Pregunta
What of the following statements about iron metabolism are FALSE?
Respuesta
-
hephaestin and ceruloplasmln are both ferrireductases, but with different localization
-
hepcidin decreases serum iron by blocking ferroportin (IREG1)
-
the major iron depot is the hemosiderin in liver
-
transferrin is a non-heme iron-transport protein
Pregunta 37
Pregunta
Which of the following statements are TRUE?
Respuesta
-
normally urine does not contain urobilinogen
-
heme oxygenase requires NADH+H+ as a cofactor
-
in prehepatic jaundice (hemolytic anemia) there is an increase of urine urobilinogen
-
hepatic (parenchymal) jaundice is characterized by increase only of indirect bilirubin
-
posthepatic (obstructive) jaundice is characterized by an increase in direct bilirubin and pale feces
Pregunta 38
Pregunta
Which of the following amino acids are essential and glucogenic?
Respuesta
-
methionine
-
cysteine
-
phenylalanine
-
valine
-
threonine
-
tryptophan
Pregunta 39
Pregunta
Which of the following biologically active compounds DO NOT derive from tyrosine?
Respuesta
-
Dopamine
-
Melanin
-
Melatonin
-
GABA
-
Epinephrine
Pregunta 40
Pregunta
Which of the following statements about heme (haem) synthesis are TRUE:
Respuesta
-
it is located in the mitochondria
-
it is located in both the mitochondria and the cytosol
-
the main regulatory enzyme is ALA synthase
-
the main regulatory enzyme is ALA dehydratase
-
porphyrias can be caused by a deficiency in ALA syntahse
-
heme is the major allosteric inhibitor and gene suppresor synthesis
Pregunta 41
Pregunta
Which of the listed biologically active compounds derive from essential and semi-essential amino acids?
Respuesta
-
NO
-
GABA
-
Histamine
-
Melanin
-
Thyroid hormones
-
Melatonin
Pregunta 42
Pregunta
Which of the following statements about purines are FALSE:
Respuesta
-
The major regulatory enzyme of "de novo" purine synthesis is ALA synthetase
-
The major regulatory enzyme of ”de novo” purine synthesis is Glutamine-PRPP amidotransferase
-
There is a cross regulation between adenosine and guanosine nucleotides production
-
PRPP is the major allosteric inhibitor of ”de novo” purine synthesis
-
Gout can be caused by decreased activity of PRPP synthetase and increased activity of hypoxanthine-guanine phosphoribosyltransferase (HPGT)
Pregunta 43
Pregunta
Which of the following statements are TRUE
Respuesta
-
normally urine does not contain bilirubin
-
bilverdin reductase converts the green pigment biliverdin into direct bilirubin using NADPH + H+ as a cofactor
-
in prehepatic jaundice (hemolytic) there are only traces of urobililinogen in urine
-
hepatic (parenchymal) jaundice is characterized by an increase in urine urobilinogen
-
posthepatic (obstructive) jaundice is characterized by an increase in direct bilirubin and dark feces
-
bilirubin-UDP glucuronosyltransferase is deficient in Gilbert's syndrome
Pregunta 44
Pregunta
Which of the following is TRUE
Respuesta
-
carbamoyl phosphate synthetase 1 is a cytosolic enzyme
-
carbamoyl phosphate synthetase 1 is a mitochondrial enzyme
-
carbamoyl phosphate synthetase 1 uses glutamine as nitrogen donor
-
carbamoyl phosphate synthetase 1 is activated by N-acetyl glutamate
Pregunta 45
Pregunta
Which of the following human proteins contain porphyrins