Test
Biochemistry Exam 5- 2nd Year-2nd Semester- PMU
Preguntas del test (45)
1Which of the following is true?
- ATransaminases are specific for only one pair of α-amino and α-keto acids
- BTransaminases co-work with Vitamin B1 (thiamine pyrophosphate) as coenzyme
- CTransaminases co-work with Vitamin B6 (pyridoxal phosphate) as coenzyme
- DTransaminases fix ammonia as amino group in amino acids
- ETransaminases release free ammonia from α-amino acids
2Which of the following a-amino acids is essential?
- AGlycine
- BGlutamate
- CSerine
- DValine
- ELysine
3Which of the following α-amino acids are glycogenic?
- ALysine, Cysteine and Proline
- BGlycine, Alanine and Proline
- CLeucine, lsoleucine and Valine
- DAspartate, Glutamate and Serine
- ELeucine, Phenylalanine and Tyrosine
4Which of the following α-amino acids is ketogenic?
- AGlycine
- BLeucine
- Clsoleucine
- DValine
- EAlanine
5Which of the following mechanisms play role in ammonia detoxification:
- AGlutamine biosynthesis in brain
- BUrea biosynthesis in muscles
- CAlanine biosynthesis in muscles
- DUrea biosynthesis in liver
- ENH4+ formation in kidney
6Which of the following statements about glutamate dehydrogenase are true:
- Athe enzyme is regulated
- Bthe enzyme is associated with the respiratory chain and the formation of energy
- Cthe enzyme uses FAD as cofactor
- Dthe enzyme uses NAD+ as cofactor
7Which of the following statements about the urea cycle are true
- Aurea catabolizes in urea cycle
- Bit does not use cell energy
- Cit has mitochondrial and cytosol phase
- Din urea cycle a toxic product is converted into less toxic product which is excreted
8Which of the following is involved in purine ring formation?
- AAlanine
- BAspartate
- CGlutamate
- DCarbamoyl phosphate
- EGlycine
9Which of the following is involved in pyrimidine ring formation?
- AAlanine
- BAspartate
- CGlutamate
- DCarbamoyl phosphate
- EGlycine
10Which of the following about GOUT is TRUE:
- Ait is characterised by elevated concentration of uric acid in blood
- Bit may be due to overproduction of purine nucleotides or decreased renal excretion of uric acid
- Cmany of the clinical symptoms arise because of the high solubility of uric acid in the aqueous environment
- Dallopurinol is used for the treatment of gout since it inhibits xanthine oxidase
11Which are the end products from pyrimidine degradation
- Auric acid
- Bβ-aminoisobutyrate
- Curea
- Dβ-alanine
- ENH3 and CO2
12Porphyrin biosynthesis occurs in:
- Acytosol
- Bmitochondria
- Cboth cytosol and mitochondria
- Dcytosol, mitochondria and cell nucleus
- Eendoplasmic reticulum
13Which of the following is correct?
- Aheme is synthesized from succinyl-CoA and glycine
- Bheme is synthesized from aspartate and carbamoyl phosphate
- Cheme is an example of iron porphyrins
- Dheme is an example of magnesium porphyrins
- Ethe clinical condition jaundice is due to elevation of bilirubin in blood plasma
14Which of the following is TRUE:
- Ain prehepatic jaundice only the direct bilirubin is increased in serum
- Bin hepatic jaundice only the indirect bilirubin is increased in serum
- Cin posthepatic (obstructive) jaundice urine urobilinogen is absent
- Dthe 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
- EGilbert Syndrome is caused by deficiency in biliverdin reductase
15Which of the following is true?
- ACarbamoyl phosphate synthetase 1 uses glutamine for the synthesis of urea
- BNH3 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
- Cclinical symptoms of ammonia intoxication include tremor, slurred speech, blurred vision, coma and ultimately death
- Da high protein diet and starvation result in induction of urea cycle enzymes
16Which of the following human proteins contain porphyrins:
- AMyoglobin
- BCyt. P450
- CCyt. C1
- DCatalase
- EFerritin
17Which of the following is NOT TRUE
- AThymidylate synthase catalyzes the synthesis of dTMP
- BH4 folate derivatives serve as one carbon donor for purine biosynthesis de novo
- Cribonucleotide reductase plays important role in RNA synthesis
- DCTP is produced by amination of UTP by CTP synthetase
18Which of the following amino acids may undergo oxidative deamination followed by energy production:
- AGlycine
- BTrytophan
- CLysine
- DGlutamate
- ECytesine
19Which of the statements about aminotransferases are TRUE
- Athey use thiamine diphosphate as a coenzyme
- Bthey use pyridoxal phosphate as a coenzyme
- Cthe ALAT content increases in cardiac infarction
- Dthe ASAT and ALAT content increases in liver disease (e.g: hepatitis)
20Which of the following compounds can accept NH2-group in transamination
- Apyruvate
- Bacetone
- Cα-ketoglutarate
- Dacetoacetate
- Eoxaloacetate
21Which of the following biogenicamines are neurotransmitters
- Aγ-aminobutyrate (GABA)
- Bserotonin
- Ctyrosine
- Ddopamine
- Eadrenaline
22Which of the following amino acids can not undergo transamination
- Alysine
- Bproline
- Calanine
- Dglutamate
- Ethreonine
23Which of the statements about aminotransferase are TRUE
- Athey use NAD + as a coenzyme
- Bthey use pyridoxal phosphate as a coenzyme
- Cthe ASAT content increases in cardiac infarction
- Dthe ASAT and ALAT content decreases in liver disease (e.g hepatitis)
24Which of the following is TRUE
- Aarginine and glycine are used for the biosynthesis of creatine
- Bcreatine phospate serves a storage form of energy in muscles, heart and brain
- Ccreatine kinase catalyses the reaction creatine phosphate -> creatinine
- Dwhen ATP is utilized as a source of energy for muscular contraction creatine phosphate maintains its concentration
25Which of the following compounds are neurotransmitters
- Aserine
- Bglycine
- Cserotonin
- Ddopamine
- Eacetylcholine
26Which of the following compounds are amino group acceptors in transaminase reactions?
- Aα-ketoglutarate
- Bacetone
- Coxaloacetate
- Dpyruvate
- Eglutamate
27Which are the end products of N-metabolism?
- ACreatine
- BCreatinine
- CUrea
- DAmmonia
- EAmmonium cations
- FUric acids
28Which of the following statements about pyrimidine synthesis are TRUE:
- APyrimidine ring is formed by adding atoms to PRPP
- BPRPP is added to the already formed pyrimidine ring
- CDerivatives of tetrahydrofolate (THF) are necessary for TMP production
- DSAM is necessary for TMP production
29What is the origin of the atoms for "de novo" purine synthesis?
- AN7, C8 and N9 from glycine
- BC4, C5 and N7 from glycine
- CC6 from CO2
- DC8 from CO2
30Which of the following statements about iron metabolism are FALSE:
- Ahemosiderin is the major iron-storage protein
- Bferritin is the major iron-storage protein
- Ctransrefin can bind only ferrous cations ( Fe3+)
- Dtransrefin can bind only ferrous cations ( Fe2+)
- Ethe major regulator of piasma iron concentration is the humoral factor hepcidin
31Which of the following compounds participate in both Krebs cycle and in transaminase reactions?
- Aoxaloacetate
- Bacetoacetate
- Cα-ketoglutarate
- Dpyruvate
- Eisocitrate
- Fmalate
32N-atom in carbamoyl phosphate, used for pyrimidine ring synthesis, derives from
- AAmmonia (NH3)
- BAspartate
- CGlutamate
- DGlutamine
- EGlycine
33Which of the following reactions from urea cycle demand ATP?
- AArginine -> Ornithine + Urea
- BOrnithine + Carbamoyl phosphate -> Citrulline
- CNH3 + CO2 -> Carbamoyl phosphate
- DCitrulline + Aspartate -> Arginosuccinate
- EArgininosuccinate -> Arginine + Fumarate
34Which of the following statements about phenylalanine degradation are TRUE?
- Aphenylalanine is hydroxylated to tyrosine
- Bphenylalanine hydroxylases uses NADPH + H+ as a cofactor
- Ca deficiency of homogentisate oxidase cause tyrosinemia type 2
- Da deficiency of phenyalanine hydroxylase results in higher concentration of phenylpyruvate, phenylpyruvate, phenyllactate and phenylacetate
- Ephenylalanine hydroxylase uses ascorbic acid as a cofactor
35Which of the following statements about "de novo“ purine synthesis are TRUE?
- APurine ring formed by adding atoms to PRPP
- BPRPP to the already formed purine ring
- CDerivatives Of tetrahydrofolate (THF) are necessary for purine synthesis
- DSAM is necessary for purine synthesis
36What of the following statements about iron metabolism are FALSE?
- Ahephaestin and ceruloplasmln are both ferrireductases, but with different localization
- Bhepcidin decreases serum iron by blocking ferroportin (IREG1)
- Cthe major iron depot is the hemosiderin in liver
- Dtransferrin is a non-heme iron-transport protein
37Which of the following statements are TRUE?
- Anormally urine does not contain urobilinogen
- Bheme oxygenase requires NADH+H+ as a cofactor
- Cin prehepatic jaundice (hemolytic anemia) there is an increase of urine urobilinogen
- Dhepatic (parenchymal) jaundice is characterized by increase only of indirect bilirubin
- Eposthepatic (obstructive) jaundice is characterized by an increase in direct bilirubin and pale feces
38Which of the following amino acids are essential and glucogenic?
- Amethionine
- Bcysteine
- Cphenylalanine
- Dvaline
- Ethreonine
- Ftryptophan
39Which of the following biologically active compounds DO NOT derive from tyrosine?
- ADopamine
- BMelanin
- CMelatonin
- DGABA
- EEpinephrine
40Which of the following statements about heme (haem) synthesis are TRUE:
- Ait is located in the mitochondria
- Bit is located in both the mitochondria and the cytosol
- Cthe main regulatory enzyme is ALA synthase
- Dthe main regulatory enzyme is ALA dehydratase
- Eporphyrias can be caused by a deficiency in ALA syntahse
- Fheme is the major allosteric inhibitor and gene suppresor synthesis
41Which of the listed biologically active compounds derive from essential and semi-essential amino acids?
- ANO
- BGABA
- CHistamine
- DMelanin
- EThyroid hormones
- FMelatonin
42Which of the following statements about purines are FALSE:
- AThe major regulatory enzyme of "de novo" purine synthesis is ALA synthetase
- BThe major regulatory enzyme of ”de novo” purine synthesis is Glutamine-PRPP amidotransferase
- CThere is a cross regulation between adenosine and guanosine nucleotides production
- DPRPP is the major allosteric inhibitor of ”de novo” purine synthesis
- EGout can be caused by decreased activity of PRPP synthetase and increased activity of hypoxanthine-guanine phosphoribosyltransferase (HPGT)
43Which of the following statements are TRUE
- Anormally urine does not contain bilirubin
- Bbilverdin reductase converts the green pigment biliverdin into direct bilirubin using NADPH + H+ as a cofactor
- Cin prehepatic jaundice (hemolytic) there are only traces of urobililinogen in urine
- Dhepatic (parenchymal) jaundice is characterized by an increase in urine urobilinogen
- Eposthepatic (obstructive) jaundice is characterized by an increase in direct bilirubin and dark feces
- Fbilirubin-UDP glucuronosyltransferase is deficient in Gilbert's syndrome
44Which of the following is TRUE
- Acarbamoyl phosphate synthetase 1 is a cytosolic enzyme
- Bcarbamoyl phosphate synthetase 1 is a mitochondrial enzyme
- Ccarbamoyl phosphate synthetase 1 uses glutamine as nitrogen donor
- Dcarbamoyl phosphate synthetase 1 is activated by N-acetyl glutamate
45Which of the following human proteins contain porphyrins
- Athe respiaratory chain cytochromes
- Bcyt P450
- Chemoglobin
- Dcatalase
- Ealbumin
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