TestWizard - EXTRA

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1. Catalyst is
1) Is always an enzyme;
2) A molecule that accelerates rates of approaching reaction equilibrium;
3) Its structure resembles the substrate of the reaction
4) Donates energy in form of enthalpy decrease for the reaction.
2. Lock and Key model:
1) Assumes that substrate binding changes the structure of the enzyme, leading to its �open� structure;.
2) Was developed by Emil Fischer and assumes perfect structural compatibility of enzyme active site and substrate;
3) Was developed by Maud Menten and assumes perfect structural compatibility of enzyme active site and substrate;
4) Was developed by Emil Fischer and assumes flexibility in the enzyme active site structure for substrate binding.
3. How would you experimentally prove that the enzymatic reaction of sucrose hydrolysis doesn�t strictly require the presence of living yeast cells?
1) Incubate in tube sucrose with pure recombinant chymosin and detect time-dependent release of glucose
2) Use growing yeast cells in a minimal medium and monitor fructose appearance in a medium;
3) Lyse yeast cells, isolate remaining cells from the specimen, incubate with sucrose, and monitor fructose�s appearance in time;
4) Lyse yeast cells, remove all cells from the specimen, isolate cell lysate and incubate it with sucrose, and monitor the appearance of fructose in time.
4. Enzymes are:
1) Inorganic catalysts that accelerate rates of approaching equilibrium;
2) Have no effect on the equilibrium of the reaction;
3) Change the equilibrium of the reaction towards
4) Accelerate the only rate of product formation, not backward reaction.
5. Enzymes lower the energy barrier of the reaction mainly by:
1) Tightly and selectively binding substrates;
2) Tightly and selectively binding and stabilizing the reaction�s transition state (TS);
3) Tightly binding and stabilizing products;
4) All the above is correct.
6. Enzymology is about making bonds and breaking the bonds. Please select the proper order of bonds found in biological molecules, from the highest energy to the lowest:
1) Hydrogen bond, van der Waals interaction, covalent bond;
2) Van der Waals interaction, hydrogen bond, covalent bond;
3) Covalent bond, hydrogen bond, van der Waals interaction;
4) Covalent bond, van der Waals interaction, ionic bond.
7. The type of bond between amino acids that lead to the formation of a polypeptide is:
1) Covalent bond;
2) Ionic bond;
3) Hydrogen bond;
4) Enzymes don�t contain secondary structures.
8. Entropy of chemical reaction:
1) Increases in irreversible, spontaneous reactions;
2) Stays constant during irreversible reaction;
3) Is always decreased in the presence of an enzyme;
4) Decreases in irreversible, spontaneous reactions.
9. Free energy (deltaG) of the A hydrolysis into B and C (A=B+C) is 10 kJ/mol. The reaction will occur:
1) Spontaneously;
2) Spontaneously and all A will be decomposed if A concentration will be over 1 M;
3) Spontaneously if coupled with B (-15kJ/mol) and C (6kJ/mol) decomposition.
10. Enzymes utilize energy carriers, often in form of ATP. Which energy carrier is characterized by deltaG lower than the one of ATP:
1) Pyrophosphate (PPi);
2) Phosphoenolpyruvate (PEP);
3) AMP;
4) GTP
11. Holoenzyme of trypsin is:
1) Is trypsin apoenzyme together with Zn co-factor;
2) The same as trypsin apoenzyme;
3) Is trypsin apoenzyme together with chymosin;
4) Is trypsin apoenzyme devoid of the catalytic triad.
12. Typical metalloproteinase:
1) Includes tryptophane in the active site for proton transfer;
2) Contains metal ions as co-factor;
3) Contains metal ions as co-enzyme;
4) Cleaves covalent bonds in polymers of metal ions.
13. The affinity for the enzyme is considered very high if:
1) Kd is over 1 M;
2) Kd is over 10 M;
3) Kd is below 1 M;
4) Kd doesn�t reflect enzyme affinity for the substrate.
14. The lifetime of the already formed Enzyme-Ligand complex is directly described by the constant:
1) DeltaG;
2) Kon;
3) Koff;
4) Km.
15. Which amino acid is chymotrypsin serves as a nucleophile during the attack on the polypeptide substrate:
1) His
2) Pro
3) Ser
4) All above
16. Which amino acids are typically found in the hydrophobic core of an enzyme?
1) Trp, Val, Ile;
2) Ser, Asp, Asn;
3) Ser, His, Asp;
4) Gly, Glu, Gln.
17. Biocatalysts are:
1) Enzymes;
2) Catalytic antibody;
3) Ribozyme;
4) All the above.
18. At constant enzyme E concentration and at low range of substrate S concentration (S lower than E) velocity of the reaction is:
1) Independent of S concentration and already reached Vmax;
2) Proportional to S concentration;
3) Constant;
4) Enzyme is not active at this S concentration given.
19. The units of Km are:
1) Amount of substrate: mol;
2) Concentration of substrate; mol/liter, M;
3) Velocity; 1/second;
4) Concentration of substance/velocity; M/second.
20. For enzyme with very low kcat (almos zero) Km approaches:
1) Kcat;
2) Equilibrium dissociation constant of ES complex (Kd);
3) Koff;
4) Kon
21. Select an enzyme characterized by the highest turnover rate:
1) Enzyme 1 (kcat � 60/min);
2) Enzyme 2 (kcat = 0.8 sec.)
3) Enzyme 3 (kcat = 10000 s-1 M-1 with km = 1 mM);
4) Enzyme 4 (kcat/km = 10000 s-1 M-1 with Km = 1 �M;
22. Competitive inhibitor:
1) Competes with the enzyme for substrate binding;
2) Occupies enzyme active site and competes for acive site with the substrate;
3) Always forms covalent bonds with the enzyme;
4) None of above is correct.
23. Organofluorophosphates (nerve gas) block:
1) Acetylcholinesterase (ACE) reversibly as E-1 complexes are decomposed by atropine;
2) Acetylcholine receptors irreversibly, forming covalent complexes;
3) Acetylcholine receptors reversibly, as inhibitor can be outcomposed by antidote in form of atropine;
4) Acetylcholinesterase (ACE) irreversibly, forming covalent E-1 complexes.
24. Competitive inhibitors cause:
1) Increase in Km, no effect on Vmax;
2) Decrease in Km, no effect on Vmax;
3) Increase in Km, decrease in Vmax;
4) No effect on Km and Vmax.
25. Assuming that you can record with spectrophotometer the appearance of product of enzymatic reaction 1 second after start of the reaction and in 1 second intervals, kinetic parameters of which enzyme you can accurately characterize at these conditions?
1) Enzyme 1 (kcat of 100/s or more);
2) Enzyme 2 (kcat lower that 1/s);
3) Enzyme 3 (kcat of 1000/s or more);
4) All the above.
26. In which of given protein groups are only enzymes:
1) Urease, hexokinase, topoisomerase, immunoglobulin G1;
2) Transaminase, phosphatase, phosphalipase C1, collagen;
3) Collagenase, carboxypeptidase, catalase, peroxidase.
4) None of above.
27. The steady state level of an enzyme in the cell is adjusted by:
1) Translation of mRNA encoding co-factor;
2) Enzyme degradation in proteasomes/lysosomes/by autophagy;
3) Translation of gene encoding co-factor;
4) All the above.
28. In the feedback inhibition of enzymatic cascade:
1) End product activates an initial enzyme of the cascade;
2) Initial product inhibits an initial enzyme of the cascade;
3) End product inhibits an initial enzyme of the cascade;
4) None of the above.
29. Regulation of enzymatic activity by reversible O-phosphorylation is manifested by:
1) The attachment of the phosphate group to the �OH group of serine of enzyme active site only;
2) The attachment of the phosphate group to �OH group of serine/threonine/tyrosine of enzyme active site only;
3) The attachment of the phosphate group to �OH group of serine/threonine/tyrosine at any place of the enzyme that affects enzymatic activity;
4) None of the above.
30. Your goal is to identify an enzyme �anti-herbicide� that could accelerate the decomposition of a toxic herbicide X of an unknown structure that is intensively used to kill weeds among the grass on the football pitch. What would be the preferable strategy to tackle this problem?
1) Isolate microorganisms from herbicide X-producing factories and perform lab tests for microbial growth on herbicide X. Follow up with enzyme gene identification.
2) Engineer enzyme �anti-herbicide� de novo based on the structure of an enzyme that decomposes �Round-up�;
3) Isolate microorganisms from herbicide X non-treated football pitch and perform lab test for microbial growth on soil from that pitch. Follow up with enzyme gene identification.
4) All the above mentioned strategies are correct.
31. In the directed evolution of enzymes, one needs to:
1) Perform screening tests of specific enzymatic activity prior introduction of enzyme diversity
2) Introduce diversity into the enzyme prior to a screening test for a specific activity;
3) Know the structure of the enzyme that is modified;
4) All the above is correct.
32. T-PA (Alteplase) is a recombinant human plasminogen activator used for the treatment of stroke and heart attack. For full activity, t-PA requires modification by glycosylation. Which production system will you swe to obtain fully active t-PA?
1) E.coli;
2) L.lactis;
3) Chines hamster ovary cells (CHO);
4) All the above can be used.
33. In Niemann-Pick lysosomal storage disease active sphingomyelinase (SM) is missing. Which version of recombinant SM could be provided as enzyme replacemen therapy to substitute missing native SM in patients with Niemann-Pick syndrome?
1) SM produced in E.coli;
2) SM produced in CHO cells modified enzymatically to expose mannose-6-phosphate;
3) SM produced in CHO cells as a fusion with transferrin, enzymatically de-glycosylated;
4) SM produced in mutant yeast cells devoid of glycosylation
34. If you would like to produce lactose free milk what will be your strategy?
1) Add recombinant lactase to the normal cow�s milk;
2) Feed cows with plant feed supplemented with lactase;
3) Pre-treat cows feed with lactase;
4) All the above is correct.
35. You are starting a company, which will produce bio-washing powder to remove strains efficiently and ecologically from lab coats of employees working in factories that produce glucose and fructose-rich diet supplements from raw plant material. What would be the preferable ingredient in bio-washing powder?
1) Mix a few rather unspecific, thermostable glycosidases.
2) Pure thermostable chymosin.
3) Highly specific, thermostable alfa-6-glycosidase;
4) Mix of peroxidases.
36. Penicillin G is an antibiotic whose mechanism of action relies on:
1) Reversible inhibition of DNA polymerase in bacteria;
2) Beta-lactam ring that ensures reversible inhibition of bacterial hexokinase;
3) Fluor nucleophile which irreversibly blocks transpeptidase of Gram-bacteria;
4) Beta-lactam ring that ensures irreversible inhibition of bacterial transpeptidase.
37. Paxlovid is a first oral pill for treatment of COVID-19 that contains:
1) Inhibitor of SARS-CoV2 major cysteine protease M-pro + inhibitor of cytochrome P450;
2) Inhibitor of cytochrome P450 only;
3) Prodrug that facilitates mutations in viral RNA;
4) Inhibitor of SARS-CoV2 major cysteine protease M-pro and recombinant cysteine protease M-pro.

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