ÚLCHBCH Medical Biochemistry 2 1. Revision Test
Correct answers
1. Select non-essential glucogenic amino acids: a) Histidine b) Cysteine c) Arginine d) Phenylalanine e) Methionine f) Proline
2. Select transamination reactions which take part in metabolism of amino acids: a) Aspartate + 2-oxoglutarate → Glutamate + Oxalacetate b) Aspartate + Alanine → Oxaloacetate + Pyruvate c) Glutamine + Pyruvate → Glutamate + Alanine d) Alanine + 2-oxoglutarate → Pyruvate + Glutamate e) Asparagine + 2-oxoglutarate → Glutamate + Aspartate f) Valine + 2-oxoglutarate → α-ketoisovalerate + Glutamate
3. Select correct pairs of amino acid (precursor) and corresponding biogenic amine: a) 5-hydroxytryptophane → tryptamine b) Lysine → putrescine c) Aspartate → GABA d) Serine → ß-alanine e) Histidine → histamine f) Ornitine → cadaverine
4. Synthesis of glutathione directly requires: a) Glutamine b) Glutamate c) γ-glutamate d) Cysteine e) Methionine f) Serine
5. Synthesis (de novo) of adrenaline directly requires: a) Tyrosine/Phenylalanine b) PLP c) Tetrahydrofolate d) Vitamin C e) Vitamin B2 f) Tetrahydrobiopterine
1
ÚLCHBCH Medical Biochemistry 2 1. Revision Test
6. Urea cycle: a) Is energetically demanding process b) Detoxifies ammonia c) Takes place entirely in cytosol d) Takes place partially in mitochondria e) Produces fumarate as a by-product f) Does not require an oxidoreductase
7. Through 2-oxoglutarate enters the citric acid cycle (CAC): a) Leucine b) Valine c) Tyrosine d) Alanine e) Threonine f) Asparagine
8. Select non-essential amino acids which are synthesized from oxaloacetate: a) Aspartate b) Lysine c) Proline d) Asparagine e) Threonine f) Isoleucine
9. Primer: a) Is an oligonucleotide b) Is a short chain of nucleic acid with free 3´-OH end c) Is enlonged by binding α-phosphate group of deoxyribonucleotide onto the 3´-OH group of growing chain d) Is an origin of complementary DNA chain synthesis in 3´→5´ direction e) Is an origin of complementary DNA chain synthesis in 5´→3´ direction f) Its synthesis is catalysed by RNA-dependent DNA polymerase
10. tRNA: a) Its biosynthesis takes place in mitochondria b) Its biosynthesis is performed by RNA polymerase III c) pre-tRNA is post-transcriptionally processed by splicing d) Primary transcript of tRNA contains -CCA sequence on its 3´-end e) Its biosynthesis takes place in nucleus f) Its purpose is transfer of short peptide for the proteosynthesis
2
ÚLCHBCH Medical Biochemistry 2 1. Revision Test
11. Select correct statements about post-translational modification of proteins: a) Is performed following termination of polypeptide chain synthesis b) Is performed by glycosylation and acylation c) Is performed by prenylation d) Is performed by hydroxylation, phosphorylation and carboxylation e) Is important for transfer of genetic information f) Is important for specific functions of proteins
12. Genetic discontinuity: a) Is characteristic for prokaryotic cells b) Is characteristic for human cells c) Refers to tandem organisation of genes d) Is not present in genes coding histones and α-interferon e) Is present in genes coding histones f) Is ensured by reproduction isolation of species
13. Replication of linear DNA molecule: a) Proceeds on both strands in direction 5´→3´ b) Is initiated by formation of replication bubbles c) In telomer region is performed by a ribonucleoprotein d) In telomer region is initiated by primer which is a hairpin with a free 3´-OH end e) In telomer region is performed by reverse transcriptase f) Its termination is caused by activity of ρ-factor
14. Biosynthesis of mRNA: a) Takes place in nucleus by action of DNA polymerase II b) Primary transcript is precursor hnRNA c) Does not require post-transcriptional modifications d) Polyadenylate tail on 3´-end of mRNA is coded by nucleic DNA e) Includes methylation as a part of post-transcriptional modifications f) Take place on Golgi apparatus
15. Inhibitors of transcription and post-transcriptional processes are: a) Cordycepin, azidothymidine b) α-amanitin, dideoxyinosine c) Plasmids d) Methylation and ethylation agents, daunomycin and adriamycin e) Tensides f) Surface-active compounds which disrupt overall charge of polynucleotide chain
3
ÚLCHBCH Medical Biochemistry 2 1. Revision Test
16. Regulation of gene expression is affected by: a) DNA methylation b) Hormone-responsive elements c) Hormones and growth factors d) RNA editing e) Transcription factors f) Repressors
17. Select correct statements regarding purine nucleotide anabolism: a) AMP is synthesized from inositolmonophosphate (IMP) in cytosol b) NAD+ a NADP+ are also synthesized from PRPP in de novo synthesis of purines c) Analogues of glutamine block the biosynthesis of purine nucleotides d) Pathologic purine deficiency is related to the excess of folic acid e) Synthesis of IMP requires glycine, glutamine, THF, aspartate and ATP f) Main regulatory enzyme of purine nucleotide synthesis is PRPP-synthase
18. Select correct statements regarding pyrimidine nucleotide metabolism: a) First reaction of biosynthesis is catalysed by CPS (carbamoyl phosphate synthase) which catalyse also the first step of urea synthesis b) Reaction which transforms deoxyuridine monophosphate into deoxythymidine monophosphate is catalysed by a lyase and requires vitamin B9 c) CPS II activity is allosterically inhibited by PRPP thus favouring synthesis of purine nucleotides d) Uridine diphosphate is metabolised into cytidine triphosphate with participation of CTP-synthetase, 2 ATP and glutamate e) Reactions of cytidine nucleotide synthesis do not require THF f) Orotate is a product of dihydroorotate dehydroxylation catalysed by dihydroorotate dehydroxylase and requires NAD+
19. Select correct statements regarding purine nucleotide metabolism: a) Guanosine is metabolised through 3 reactions into a product, which can be accumulated in soft tissues as a result of genetic disorder of PRPP synthase activity b) Xanthinoxidase is a reductase which catalyses reduction of xanthine into uric acid by oxidising H2O into H2O2 c) Increased concentration of sodium urate can lead to nephropathy d) Dysfunctional hypoxynthine-guanine phosphoribosyltransferase leads to hypouricemia - called Lesch-Nyhanov syndrome e) Decreased PRPP production (precursor ribose-5-P) leads to decreased purine synthesis - called von Gierke disease f) Xanthine oxidase deficiency is exhibited by hypouricemia
4
ÚLCHBCH Medical Biochemistry 2 1. Revision Test
20. Select correct statements regarding purine/pyrimidine nucleotide metabolism: a) CO2, NH3, β-alanine a β-aminoisobutyrate which are water insoluble are produced by degradation of pyrimidine nucleotides b) Increased activity of dihydropyrimidine dehydrogenase causes β-hydroxybutyrate aciduria c) Uracil a thymine are transformed into dihydrouracil a dihydrothymine, respectively, by common enzyme dihydropyrimidine dehydrogenase which re-oxidise NADPH to NADP+ d) Amino acid formed by degradation of U/T/C nucleotides is not proteinogenic e) β-aminoisobutyrate is by transamination and subsequent reaction with CoA transformed into succinyl-CoA which can enter citric acid cycle f) Pseudouridine is a pyrimidine nucleotide formed by RNA degradation and excreted into urine without a change
21. Assign statements a) – h) to the corresponding type of the reaction (and add additional information): Transamination: b, c, e, h Deamination: a, d Decarboxylation: f, g
a) Products are oxoacids and NH3 b) Is catalysed by enzymes which transfer amino groups of most amino acids (AAs) to 2- oxoacids (Write the name of corresponding enzymes in general) Aminotransferases (transaminases) c) A coenzyme which is used to bind AA is one of the vitamins (Give name of vitamin and full name of its active form) Vitamin B6, PLP d) Required coenzymes include FMN, FAD or NAD+, NADP+ (Specify name of enzyme group in general MAO, Oxid. deaminase (GDH) e) Importance of this reaction is also in synthesis of certain non-essential AAs f) Very active compounds – biogenic amines are produced by this type of reaction (Name at least 4 biogenic amines and specify their role) e.g. Asp → β-alanine (part CoA) Glu → GABA (neurotransmiter) Ser → ethanolamine (part phospholipids) His → histamine (neuratransmiter, immunity) g) Products of this reaction include neurotransmitters (Name at least 2 of them) GABA, histamine, dopamine h) Increased activity of some enzymes catalysing these reactions in blood serum is observed during liver and heart diseases (Specify these enzymes) ALT, AST 5
ÚLCHBCH Medical Biochemistry 2 1. Revision Test
22. Identify processes (cycles) 1, 2 as well as compounds A-Q: a) Compound A is produced in cycle 1 b) Compound B is produced also in cycle 1 c) Compound A can be formed also by a reaction catalysed by a transferase from C d) By a reaction of the same type compound B can be formed from compound D e) Reaction of compound C with a small molecule E yields compound F f) In the same way compound D reacts with E to form compound G g) If a different small molecule H is broken off from compound C, compound I is formed h) In the same way compound D can react to form compound J i) Compounds D, E a H enter cycle 2 which produces compounds K and L j) Compound L is also produced in cycle 1 k) Cycle 2 produces also compound M which enters cycle 1 through compound A which is produced from compound C l) Compound M can be used to produce compound N especially important for muscles by a series of reactions m) Compounds D, F a H create hydrocarbon structure (skeleton) of compounds O which are important for storing genetic information n) Compounds D, F, H along with amino acid P take part in formation of different compounds Q which are important for storing genetic information as well
Cycle 1: CAC Cycle 2: urea cycle A 2-oxoglutarate G Asn M Arg
B Oxalacetate H CO2 N creatine C Glu I GABA O pyrimidine D Asp J β-alanine P Gly
E NH3 K urea Q purine F Gln L fumarate
6
ÚLCHBCH Medical Biochemistry 2 1. Revision Test
23. Answer questions regarding compounds A – F:
A B C
D E F a) Write amino acids which serve as precursors for the given compounds. A Tyr (Phe) D Ser B Trp E Orn (Arg) C Trp F Arg
b) Which of the given compounds require PLP (Vitamin B6) for their biosynthesis? A – E c) Which of the given compounds require SAM for their biosynthesis? A, C, D, E d) Which of the given compounds require THBP (tetrahydrobiopterin) for their biosynthesis? A, B, C, F e) Which of the given compounds require CoA (coenzyme A) for their biosynthesis? C, D f) Which of the given compounds belong to hormones? A, C g) Which of the given compounds belong to neurotransmitters? A, B, D, F h) Which of the given compounds are produced in brain? A – F (všetky)
7
ÚLCHBCH Medical Biochemistry 2 1. Revision Test
24. Answer questions regarding compounds A – F:
A B C
D E F a) Which of the given compounds require glycine for their biosynthesis? A, B, C b) Which of the given compounds require vitamin B9 for their biosynthesis? A, B, C, E c) Which of the given compounds require CPS II enzyme for their biosynthesis? D, E, F d) Which of the given compounds are present in form of their nucleotides in tRNA? A, C, D, F e) Which of the given compounds is present in nucleoside denoted ψ? F f) Which of the given compounds are intermediates of purine degradation? A, B g) Which of the given compounds are formed by action of molybdenum-containing enzyme? B h) Which of the given compounds is a direct precursor of plant secondary metabolites found in coffee and cocoa beans? (Specify these metabolites) B (theobromine, caffeine)
25. Transcribe DNA sequence of the template strand into mRNA and translate it into amino acid sequence of the polypeptide chain. DNA: 3´- TAC-CAT-TTT-TCA-GGT-CAA-ACA-CTT-CCC-GTA-ATT - 5´ mRNA: 3´- AUG-GUA-AAA-AGU-CCA-GUU-UGU-GAA-GGG-CAU-UAA - 5´ Peptide: N-Met-Val-Lys-Ser-Pro-Val-Cys-Glu-Gly-His-(Stop)-C
8