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Biochemistry Exam 5- 2nd Year-2nd Semester- PMU

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Biochemistry Exam 5- 2nd Year- PMU
Med Student
Quiz by Med Student , updated more than 1 year ago
Med Student
Created by Med Student over 7 years ago
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Question 1

Question
Which of the following is true?
Answer
  • 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

Question 2

Question
Which of the following a-amino acids is essential?
Answer
  • Glycine
  • Glutamate
  • Serine
  • Valine
  • Lysine

Question 3

Question
Which of the following α-amino acids are glycogenic?
Answer
  • Lysine, Cysteine and Proline
  • Glycine, Alanine and Proline
  • Leucine, lsoleucine and Valine
  • Aspartate, Glutamate and Serine
  • Leucine, Phenylalanine and Tyrosine

Question 4

Question
Which of the following α-amino acids is ketogenic?
Answer
  • Glycine
  • Leucine
  • lsoleucine
  • Valine
  • Alanine

Question 5

Question
Which of the following mechanisms play role in ammonia detoxification:
Answer
  • Glutamine biosynthesis in brain
  • Urea biosynthesis in muscles
  • Alanine biosynthesis in muscles
  • Urea biosynthesis in liver
  • NH4+ formation in kidney

Question 6

Question
Which of the following statements about glutamate dehydrogenase are true:
Answer
  • 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

Question 7

Question
Which of the following statements about the urea cycle are true
Answer
  • 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

Question 8

Question
Which of the following is involved in purine ring formation?
Answer
  • Alanine
  • Aspartate
  • Glutamate
  • Carbamoyl phosphate
  • Glycine

Question 9

Question
Which of the following is involved in pyrimidine ring formation?
Answer
  • Alanine
  • Aspartate
  • Glutamate
  • Carbamoyl phosphate
  • Glycine

Question 10

Question
Which of the following about GOUT is TRUE:
Answer
  • 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

Question 11

Question
Which are the end products from pyrimidine degradation
Answer
  • uric acid
  • β-aminoisobutyrate
  • urea
  • β-alanine
  • NH3 and CO2

Question 12

Question
Porphyrin biosynthesis occurs in:
Answer
  • cytosol
  • mitochondria
  • both cytosol and mitochondria
  • cytosol, mitochondria and cell nucleus
  • endoplasmic reticulum

Question 13

Question
Which of the following is correct?
Answer
  • 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

Question 14

Question
Which of the following is TRUE:
Answer
  • 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

Question 15

Question
Which of the following is true?
Answer
  • 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

Question 16

Question
Which of the following human proteins contain porphyrins:
Answer
  • Myoglobin
  • Cyt. P450
  • Cyt. C1
  • Catalase
  • Ferritin

Question 17

Question
Which of the following is NOT TRUE
Answer
  • 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

Question 18

Question
Which of the following amino acids may undergo oxidative deamination followed by energy production:
Answer
  • Glycine
  • Trytophan
  • Lysine
  • Glutamate
  • Cytesine

Question 19

Question
Which of the statements about aminotransferases are TRUE
Answer
  • 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)

Question 20

Question
Which of the following compounds can accept NH2-group in transamination
Answer
  • pyruvate
  • acetone
  • α-ketoglutarate
  • acetoacetate
  • oxaloacetate

Question 21

Question
Which of the following biogenicamines are neurotransmitters
Answer
  • γ-aminobutyrate (GABA)
  • serotonin
  • tyrosine
  • dopamine
  • adrenaline

Question 22

Question
Which of the following amino acids can not undergo transamination
Answer
  • lysine
  • proline
  • alanine
  • glutamate
  • threonine

Question 23

Question
Which of the statements about aminotransferase are TRUE
Answer
  • 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)

Question 24

Question
Which of the following is TRUE
Answer
  • 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

Question 25

Question
Which of the following compounds are neurotransmitters
Answer
  • serine
  • glycine
  • serotonin
  • dopamine
  • acetylcholine

Question 26

Question
Which of the following compounds are amino group acceptors in transaminase reactions?
Answer
  • α-ketoglutarate
  • acetone
  • oxaloacetate
  • pyruvate
  • glutamate

Question 27

Question
Which are the end products of N-metabolism?
Answer
  • Creatine
  • Creatinine
  • Urea
  • Ammonia
  • Ammonium cations
  • Uric acids

Question 28

Question
Which of the following statements about pyrimidine synthesis are TRUE:
Answer
  • 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

Question 29

Question
What is the origin of the atoms for "de novo" purine synthesis?
Answer
  • N7, C8 and N9 from glycine
  • C4, C5 and N7 from glycine
  • C6 from CO2
  • C8 from CO2

Question 30

Question
Which of the following statements about iron metabolism are FALSE:
Answer
  • 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

Question 31

Question
Which of the following compounds participate in both Krebs cycle and in transaminase reactions?
Answer
  • oxaloacetate
  • acetoacetate
  • α-ketoglutarate
  • pyruvate
  • isocitrate
  • malate

Question 32

Question
N-atom in carbamoyl phosphate, used for pyrimidine ring synthesis, derives from
Answer
  • Ammonia (NH3)
  • Aspartate
  • Glutamate
  • Glutamine
  • Glycine

Question 33

Question
Which of the following reactions from urea cycle demand ATP?
Answer
  • Arginine -> Ornithine + Urea
  • Ornithine + Carbamoyl phosphate -> Citrulline
  • NH3 + CO2 -> Carbamoyl phosphate
  • Citrulline + Aspartate -> Arginosuccinate
  • Argininosuccinate -> Arginine + Fumarate

Question 34

Question
Which of the following statements about phenylalanine degradation are TRUE?
Answer
  • 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

Question 35

Question
Which of the following statements about "de novo“ purine synthesis are TRUE?
Answer
  • 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

Question 36

Question
What of the following statements about iron metabolism are FALSE?
Answer
  • 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

Question 37

Question
Which of the following statements are TRUE?
Answer
  • 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

Question 38

Question
Which of the following amino acids are essential and glucogenic?
Answer
  • methionine
  • cysteine
  • phenylalanine
  • valine
  • threonine
  • tryptophan

Question 39

Question
Which of the following biologically active compounds DO NOT derive from tyrosine?
Answer
  • Dopamine
  • Melanin
  • Melatonin
  • GABA
  • Epinephrine

Question 40

Question
Which of the following statements about heme (haem) synthesis are TRUE:
Answer
  • 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

Question 41

Question
Which of the listed biologically active compounds derive from essential and semi-essential amino acids?
Answer
  • NO
  • GABA
  • Histamine
  • Melanin
  • Thyroid hormones
  • Melatonin

Question 42

Question
Which of the following statements about purines are FALSE:
Answer
  • 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)

Question 43

Question
Which of the following statements are TRUE
Answer
  • 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

Question 44

Question
Which of the following is TRUE
Answer
  • 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

Question 45

Question
Which of the following human proteins contain porphyrins
Answer
  • the respiaratory chain cytochromes
  • cyt P450
  • hemoglobin
  • catalase
  • albumin
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