Worksheetsbiochem-mid-107
Total questions: 48
Worksheet time: 24mins
Name
Class
Date
1.
1. Concerning protein denaturation and folding, which the following description is not correct?
a)
A. As proteins are synthesized on ribosomes, more often they fold into their native conformations spontaneously.
b)
B. Loss for protein structure results in loss of function.
c)
C. Loss of structure results in wrong localization where they gain of function.
d)
D. Proteins that are not properly folded often have exposed hydrophobic surfaces, leading to the formation of inactive aggregates.
2.
2. According to thermodynamical theory, the unfolded state of protein can be characterized by:
a)
A. high free energy and high conformational entropy
b)
B. low free energy and low conformational entropy
c)
C. high free energy and flow conformational entropy
d)
D. low free energy and high conformational entropy
3.
3. Which of the following statement about Hemoglobin (Hb) and 2，3-BPG for oxygen binding is not true?
a)
A. Maternal Hb binds 2,3-BPG more than fetal does
b)
B. 2,3-BPG binds Hb more in R-state than in T-state
c)
C. Oxygen affinity of fetal red blood cells is higher than that of the maternal
d)
D. The 2,3-BPG concentration in normal human blood is about 5 mM at sea level and about 8 mM at 4500 M altitudes.
4.
4. A protein binds to its ligand with a Kd of 5 x 10-8 M, at what concentration of the ligand will be 0.2?
a)
A. 1.25x10-8
b)
B. 2x10-8
c)
C. 5x10-8
d)
D. 7.5x10-8
5.
5. Which of the protein-ligand pairs has relative higher Kd value?
a)
A. enzyme-substrate
b)
B. antigen-antibodies
c)
C. insulin-insulin receptor
d)
D. avidin-biotin.
6.
6. The conversion of _________ represents a conservative change while the conversion of _________ represents a nonconservative change.
a)
A. Asp to Arg; Ile to Ser
b)
B. Tyr to Phe; Lys to Arg
c)
C. Gln to Asn; Ser to Thr
d)
D. Ile to Leu; Asn to Ala
7.
7. Which of the following is true regarding the α-carbon of an amino acid?
a)
A. there are always four different functional groups attached
b)
B. the most commonly occurring form of amino acids are the D-amino acids
c)
C. for all amino acids except glycine, the α-carbon is a stereocenter
d)
D. all of the above
8.
8. At a pH of 5, all amino acids have at least ___ charged group(s) and at most, ____ charged group(s).
a)
A. 0；1
b)
B. 1；2
c)
C. 2；3
d)
D. 2；4
9.
9. Which of the following pairs of amino acids could form a charge-charge interaction through their R-groups?
a)
A. methionine and histidine
b)
B. glutamine and lysine
c)
C. serine and glutamic acid
d)
D. aspartate and arginine
10.
10. Which of the following amino acid undergoes an oxidation reaction to form a disulfide bond?
a)
A. Serine
b)
B. Cysteine
c)
C. Methionine
d)
D. None of the above
11.
11. Which of the following amino acids is incorporated into proteins during ribosomal protein synthesis?
a)
A. 5-hydorxylysine
b)
B. selenocysteine
c)
C. 4-hydroxyproline
d)
D. phosphoserine
12.
12. Which of the following bonds has partial double bond character?
a)
A. 1
b)
B. 2
c)
C. 3
d)
D. 4
13.
13. If a cis peptide bond is found in a protein, the most likely amino acid to contribute the amine to the amide bond is?
a)
A. phenylalanine
b)
B. leucine
c)
C. proline
d)
D. glycine
14.
14. Given the following peptide, what would be the overall charge at PH=5? Met-Glu-Ser-Arg-His-Phe-Pro-Asn-Ala-Glu-Cys-Ala-Ser
a)
A. +2
b)
B. +1
c)
C. 0
d)
D. -1
e)
E. -2
15.
15. Which is not correct regarding electrospray ionization (ESI)-mass/mass spectrometry?
a)
A. b- and y-ion protein normally acquires one or two protons, and thus positive charges
b)
B. usually coupled with liquid chromatography
c)
C. collision gas for peptide fragmentation
d)
D. a protein normally acquires one or two protons, and thus positive charges
16.
16. When you work on an unknown protein purification using chromatography approach coupled with functional assay. The interesting fraction will be further analyzed by which of the following procedures.
a)
A. SDS-PAGE and Edman degradation
b)
B. SDS-PAGE and immunoblotting
c)
C. SDS-PAGE and ESI-MS/MS
d)
D. sequencing the DNA of the protein’s corresponding gene
17.
17. Which amino acid is often referred to as a “helix-breaker” due to its absence fromα-helices but is often found in structures such as β-turns?
a)
A. Val
b)
B. Met
c)
C. Pro
d)
D. Phe
18.
18. Which technique can serve as a benchmark for the folded state, useful for monitoring denaturation or conformational changes brought about by changes in solution conditions?
a)
A. Western blotting
b)
B. CD spectrum
c)
C. X-ray crystallography
d)
D. ELISA
19.
19. Which of the following statements concerning ion-exchange chromatography is correct?
a)
A. Diethylaminoethyl (DEAE)-Sepharose belongs to cation exchanger
b)
B. PH and or salt gradient of mobile phase can elute the bond proteins
c)
C. A protein (pI=5.0) can bind onto CM(carboxy-methyl) beads at PH=6.0
d)
D. To bind onto DEAE beads, PH of binding buffer should be lower than pI of the target protein
20.
20. Prion protein misfolding is not related to chich of the following?
a)
A. an infectious agent
b)
B. conversing Pr𝑃C 𝑡𝑜 𝑃𝑟𝑃SC
c)
C. Creutzfeldt-Jakob disease
d)
D. beta-sheet to alpha-helix conversation in N-terminus
21.
21. The structural classification of proteins is based primarily on their:
a)
A. amino acid sequence
b)
B. evolutionary relationships
c)
C. function
d)
D. motif
22.
22. Jellyfish produces green fluorescent protein (GFP). The source of the fluorescence is a group formed by the spontaneous rearrangement and oxidation of the sequence Ser-X-Gly within the center of the protein. Where X could be:
a)
A. Tyr
b)
B. Glu
c)
C. Ala
d)
D. Gln
23.
23. Concerning western blot , which of the following is not correct?
a)
A. a method to analyze protein expression level
b)
B. detecting a protein on PVDF membrane
c)
C. usually secondary antibodies are labeled
d)
D. using specific antibody to detect protein purity
24.
24. The deficiency of what vitamin could cause the disease of pellagra.
a)
A. Thiamine
b)
B. folic acid
c)
C. riboflavin
d)
D. niacin
25.
25. Hexokinase(EC 2.7.1.2) catalyzes the reaction of glucose with ATP to form glucose 6-phosphate. It belongs to which classification:
a)
A. Transferase
b)
B. Oxidoreductase
c)
C. Hydrolase
d)
D. Lyase
26.
26. Enzyme catalyzes the reaction by lower -∆S’ through
a)
A. covalent bond with substrate
b)
B. tight binding with substrate
c)
C. a proximity and orientation to bind with substrate
d)
D. strong binding with transition state
27.
27. Aspartate carbamoyltransferase(ATCase) , a multisubunit protein consisting of 6 catalytic subunits and 6 regulatory subunits , is involved in allosteric control of pyrimidine biosynthesis:
a)
A. ATCase is feedback activation by CTP through the binding at catalytic subunits
b)
B. ATCase is feedback activation by ATP through the binding at regulatory subunits
c)
C. ATCase is feedback inhibition by UTP through the binding at catalytic subunits
d)
D. PALA , a bisubstrate analog , binding stabilizes the T state
28.
28. One of the enzymes involved in glycolysis , aldolase , requires zinc for catalysis. Under conditions of zinc deficiency , when the enzyme may lack zinc , it would be referred to as the :
a)
A. coenzyme
b)
B. apoenzyme
c)
C. holoenzyme
d)
D. prosthetic group
29.
29. The Mechaelis-Menten equation for enzyme catalyzed reaction is
a)
A. 1/v= VmaxS/(Km+S)
b)
B. 1/v= (1/Vmax)+(Km/Vmax)(S)
c)
C. v= KmS/( Vmax+S)
d)
D. v=( VmaxS)/( Km+S)
30.
30. Both water and glucose share an –OH that can serve as a substrate for a reaction with the terminal phosphate of ATP catalyzed by hexokinase. Glucose, however, is about a million times more reactive as a substrate than water. The best explanation is that:
a)
A. The larger glucose binds better to the enzyme; it induces a conformational change in hexokinase that brings active-site amino acids into position for catalysis.
b)
B. Glucose has more –OH groups pre molecule than does water.
c)
C. Water and the second substrate, ATP, compete for the active site resulting in a competitive inhibition of the enzyme.
d)
D. The –OH group of water is attached to an inhibitory H atom, while the glucose –OH group is attached to C.
31.
31. The vitamin folate can be converted the coenzyme tetrahydrofolate which is involved in the what enzymatic reaction.
a)
A. transamination
b)
B. acyl group transfer
c)
C. transfer of one-carbon components
d)
D. phosphorylation
32.
32. The inhibitor is structurally similar to the substrate for the enzyme that covalently modify active site residues. This inhibitor is classified as
a)
A. Reversible inhibitor
b)
B. Group specific inhibitor
c)
C. Affinity label
d)
D. Suicide inhibitor
33.
33. When every enzyme molecule in the reaction mixture has its substrate-binding site occupied by substrate, it is considered __________ and the velocity is __________.
a)
A. Complementary; Vmax
b)
B. Saturated; Vmax
c)
C. Saturated; Vmax/Km
d)
D. Inhibited; Vmax/2
34.
34. For the V system of the MWC model, the half-maximum velocity(K0.5) __________ in response to inhibitor, Vmax __________
a)
A. Remains constant; is decreased
b)
B. Is decreased; is increased
c)
C. Is changed; remains constant
d)
D. Remains constant; is increased
35.
35. HIV protease is belong to __________:
a)
A. Serine protease; covalent catalysis
b)
B. Cysteine protease; covalent electrophilic catalysis
c)
C. Aspartate protease; general base-general acid catalysis
d)
D. Metal protease; general base-general acid catelysis
36.
36. Clavulanic is a mechanism-based inhibitor for __________.
a)
A. HIV protease
b)
B. transpeptidase
c)
C. B-lacamase
d)
D. lysozyme
37.
37. The value of kcat indicates an enzyme property of
a)
A. A measure of efficiency
b)
B. A measure of specificity
c)
C. Affinity of substrate
d)
D. The catalytic constant
38.
38. What is the v/V ratio when [S] =4Km ?
a)
A. 0.4
b)
B. 0.5
c)
C. 0.8
d)
D. 1
39.
39. The overall free energy change for a reaction is related to ______ , and the rate constant for a reaction is related to ______.
a)
A. the free energy of activation ; the equilibrium constant.
b)
B. the equilibrium constant ; the free energy of activation
c)
C. the translation state ; the free energy of activation
d)
D. the equilibrium constant ; the intermediate
40.
40. In the hydrolysis of p-nitrophenylacetate by chymotrypsin:
a)
A. The first product is acetic acid.
b)
B. An acetyl-enzyme intermediate forms during the mechanism.
c)
C. The kinetic mechanism is sequential.
d)
D. The initial rate for p-nitrophenolate display lag kinetics.
41.
41. The active-site Ser of tranpeptidase attacks the carbonyl of the peptide bond between the two ______residues，creating a covalent ester linkage between the substrate and the enzyme.
a)
A. D-alanine
b)
B. L-phenylalanine
c)
C. L-lysine
d)
D. D-histidine
42.
42. All of the following statements about noncompetitive inhibition are true EXCEPT:
a)
A. They interact with the enzyme as well as the enzyme-substrate complex.
b)
B. Increasing the concentration of [S] can overcome the inhibition.
c)
C. The Vmax value does not remain the same as for a reaction that is not inhibited.
d)
D. The inhibitor binds to a different site than does the substrate
43.
43. Organic fluorophosphates like DIPF reacts with ____ group of serine protease. They are ____ inhibitors.
a)
A. Serine; competitive
b)
B. Tyrosine; competitive
c)
C. Hisitidine; irreversible
d)
D. Serine; irreversible
44.
44. Catalytic antibodies, also called ___, are generated against an antigen that is:
a)
A. Abzymes; an analog of the transition-state intermediate in the reaction
b)
B. Abzymes; the substrate of the reaction
c)
C. Zymogens; an analog of the product of the reaction
d)
D. Holoenzyme; analog of the transition-state intermediate in the reaction
45.
45. The role of the residue Ser195 in the chymotrypsin is participated in
a)
A. Electrostatic catalysis
b)
B. The metal ion catalysis
c)
C. The nucleophilic catalysis
d)
D. The acid-base catalysis
46.
46. Emil Fischer proposes model for an enzyme/substrate pair. It explains the specificity of enzyme/substrate pairs, it does little to explain catalysis. It is
a)
A. Induce fit model
b)
B. Concerted model
c)
C. Sequential model
d)
D. Lock=and-key model
47.
47. The steady-state kinetic for the both substrates shows the following initial rate pattern. What kind of kinetic mechanism can be concluded for the enzymecatalyzed reaction?
a)
A. Sequential random
b)
B. Sequential ordered
c)
C. Ping-pong
d)
D. Sequential ping-pong
48.
48. Indicate the type of inhibition for the following inhibition scheme:
a)
A. Competitive inhibition
b)
B. Noncompetitive inhibition
c)
C. Uncompetitive inhibition
d)
D. Irreversible
100 %
