Biochemistry Lab Final Question

77 Questions | Total Attempts: 497

SettingsSettingsSettings
Please wait...
Chemistry Quizzes & Trivia

Questions are from sample quizzes and final


Questions and Answers
  • 1. 
    The term "blotting" refers to:
    • A. 

      Running the gel in the presence of SDS

    • B. 

      Digesting the DNA with restriction enzyme

    • C. 

      Transfer of biomolecules to an immobilizing membrane

    • D. 

      Disrupting the disulfide bonds of proteins in the presence of (beta) mercaptoethanol

  • 2. 
    Check all choices that do not belong to transfer buffer:
    • A. 

      Methanol

    • B. 

      Tris-buffer

    • C. 

      SDS

    • D. 

      Acetone

    • E. 

      Glycine

    • F. 

      2-mercaptoethanol

  • 3. 
    Which reagent was used for total protein detection in your Western blot lab? 
    • A. 

      Ninhydrin spray

    • B. 

      Silver stain

    • C. 

      Colloidal gold reagent

    • D. 

      Copper stain

  • 4. 
    RNA blot refers to:
    • A. 

      Western blot

    • B. 

      Northern blot

    • C. 

      Southern blot

    • D. 

      Eastern blot

  • 5. 
    What are the basic steps required for biological molecules' detection using western blot technique? 
    • A. 

      Electrophoretic separation of protein

    • B. 

      Transfer and immobilization onto a membrane

    • C. 

      Binding of probe molecule to the target molecules on the membrane

    • D. 

      Visualization of bound protein

  • 6. 
    The mobility of portein bands in Western blotting is from anode (postive pole) to cathode (negative)
    • A. 

      True

    • B. 

      False

  • 7. 
    Most proteins have postive charge above pH 7.0
    • A. 

      True

    • B. 

      False

  • 8. 
    Blocking step in western blot detection is used to increase nonspecific binding
    • A. 

      True

    • B. 

      False

  • 9. 
    Which of the following is the proper component sequence in western blotting: 
    • A. 

      Fiber pad, filter paper, nitrocellulose membrane, gel, filter paper, fiber pad

    • B. 

      Fiber pad, nitrocellulose membrane, filter paper, gel, filter paper, fiber pad

    • C. 

      Fiber pad, filter paper, gel nitrocellulose membrane filter paper, fiber pad

    • D. 

      Fiber pad, nitrocellulose membrane, filter paper, gel, filter paper, fiber pad

  • 10. 
    The use of methanol in transfer buffer of western blotting is
    • A. 

      To increase negative charge of proteins to be transferred

    • B. 

      To dissociate the SDS from proteins and facilitate to move from gel to NC membrane

    • C. 

      To increase the dielectric constant

    • D. 

      Methanol has nothing to do with western blotting

  • 11. 
    Bell shape curve in an enzyme characterization is a represenative of: 
    • A. 

      PH only

    • B. 

      Temperature only

    • C. 

      Enzyme concentration only

    • D. 

      A and c

    • E. 

      A and b

  • 12. 
    What will be the inital velocity (Vo) for an enzyme that has Km =2s
    • A. 

      1/3 Vmax

    • B. 

      1/2 Vmax

    • C. 

      2/3 Vmax

  • 13. 
    Which of the following statement(s) is ture about lysozyme enzyme?
    • A. 

      Provide defense mechanism against bacterial infection

    • B. 

      Cleaves the glycosidic bond

    • C. 

      Eggwhite is the source for this enzyme

    • D. 

      All of the statements are true

  • 14. 
    One international unit of an enzyme is defined as the amount that catalyzes:
    • A. 

      The formation of one mmol of product in one min

    • B. 

      The formation of one micromol of product in one min

    • C. 

      The formation of one mol of product in one min

    • D. 

      The formation of one micromol of product in one hour

  • 15. 
    When [S] <
    • A. 

      The reaction is in zero order of reaction

    • B. 

      The reaction is in first order of reaction

    • C. 

      The product formation is directly related to the substrate concentration

    • D. 

      It is the substrate concentration that equals the Km estimate

    • E. 

      B and c

  • 16. 
    If Vmax = 150 micromol/sec and Km = 2mM, what is the initial velocity at  [S]= 10 mM? 
    • A. 

      125 micromoles/sec

    • B. 

      91 micromoles/sec

    • C. 

      125 micromol/min

    • D. 

      300 micromol/sec

  • 17. 
    Wht is the v/Vmax ratio if [S]=3Km?
    • A. 

      75

    • B. 

      0.75

    • C. 

      0.25

    • D. 

      None

  • 18. 
    In the last experiment, you added lysozyme just before recording the absorbance reading. At the end of reaction, you noticed clear assay solution. What could be the reason? Is it..
    • A. 

      The enzyme cleaves the hydrogen bond and disrupts the cell wall that becomes clear

    • B. 

      The enzyme cleaves the disulfide bond and disrupts the cell wall that becomes clear

    • C. 

      The enzyme cleaves the glycosidic bond and disrupts the cell wall that becomes clear

  • 19. 
    Enzymes increase the rate of reaction by:
    • A. 

      Increasing the free energy of activation

    • B. 

      Increasing the free energy change of the reaction

    • C. 

      Decreasing the nergy of activation

    • D. 

      None of the above

  • 20. 
    A 0.2 ml pure Muramidase (2.5 mg/ml) hydrolyzed 0.2 mmol of cell wall in 5 minutes. What is the specific activity? 
    • A. 

      40 micromole/min/mg

    • B. 

      0.04 millimol/min/mg

    • C. 

      80 micromol/min/mg

    • D. 

      None of the above

  • 21. 
    Modified by a suitable inhibitor
    • A. 

      Km

    • B. 

      Vmax

    • C. 

      Ki

  • 22. 
    Changed in the presence of competitive inhibitor 
    • A. 

      Km

    • B. 

      Vmax

    • C. 

      Ki

  • 23. 
    Changed in the presence of noncompetitive inhibitor 
    • A. 

      Km

    • B. 

      Vmax

    • C. 

      Ki

  • 24. 
    Changed in the presence of uncompetitive inhibitor
    • A. 

      Km

    • B. 

      Vmax

    • C. 

      Ki

  • 25. 
    Gives approximate substrate concentration within the cell 
    • A. 

      Km

    • B. 

      Vmax

    • C. 

      Ki

  • 26. 
    Which of the follwoing is noncompetitive inhibitor for acid phosphatase? 
    • A. 

      Sodium arsenate

    • B. 

      Sodium fluoride

    • C. 

      Sodium phosphate

    • D. 

      PNPP

  • 27. 
    Which of the following method did you use for calculating Ki in the enzyme inhibition lab?
    • A. 

      Michaelis- Menten equation

    • B. 

      Dixon plot

    • C. 

      Eadie-Hofstee plot

    • D. 

      None of the above

  • 28. 
    In competitive inhibiton, the inhibitor binds to the: 
    • A. 

      ES complex

    • B. 

      Free enzyme

    • C. 

      Both free enzyme and ES complex

    • D. 

      None of the above

  • 29. 
    Which of the following expressino is used for determination of Km? 
    • A. 

      Vo at 1/2 Vmax

    • B. 

      [S] at 1/2 Vmax

    • C. 

      [P] at 1/2 Vmax

    • D. 

      [S] at Vmax

  • 30. 
    Substances generally form covalent  bonds with a specific functional group in an enzyme's active site are categorized as
    • A. 

      Competitive inhibitor

    • B. 

      Uncompetitive inhibitor

    • C. 

      Irreversible inhibitors

    • D. 

      Noncompetitive inhibitors

  • 31. 
    Which property of proten best determines the electrophoretic pattern in SDS-PAGe under reducing conditions? 
    • A. 

      Shape of the native protein

    • B. 

      Molecular weight of subunits

    • C. 

      Specific binding sites on the native proten

    • D. 

      Net charge of the native protein

    • E. 

      All of the above

  • 32. 
    Which reagent/ chemical initiate polymerization in gel electrophoresis? 
    • A. 

      TEMED

    • B. 

      Ammonium persulfate

    • C. 

      Acrylamide

    • D. 

      2-mercaptoethanol

    • E. 

      SDS

  • 33. 
    Proteins that are to be separted in SDS-PAGE are subjected to treat with all of the follwing reagents except: 
    • A. 

      Heat

    • B. 

      SDS

    • C. 

      B-mercaptoethanol

    • D. 

      Ammonium persulfate

  • 34. 
    Which tracking dye did you use in SDS=PAGE?
    • A. 

      Coomassie blue

    • B. 

      Bromophenol blue

    • C. 

      Bromothymol blue

    • D. 

      DTT

  • 35. 
    The polymerized gel is an ideal gel matrix that provides desired prosity and is toxic after polymerization 
    • A. 

      True

    • B. 

      False

  • 36. 
    The presence of glycerol in sample buffer increasese the density of protein sample and facilitates to prevent from diffision in the sample well 
    • A. 

      True

    • B. 

      False

  • 37. 
    At low pH, TEMED may become deprotonated and results in slower polymerization 
    • A. 

      True

    • B. 

      False

  • 38. 
    A protein mixture having a MW of 2,000 23000 and 40,000 daltons was electrophoresed in SDS-PAGE system. Which protein will be at the bottom of gel? 
    • A. 

      A protein with MW of 40,000 daltons

    • B. 

      A protein with MW of 23000 daltons

    • C. 

      A protein with MW of 2,000 daltons

    • D. 

      All of them will be in one band

  • 39. 
    The rate of migration of a protein in electrophoresis depends upon the 
    • A. 

      Time of electrophoresis

    • B. 

      Electrical potential

    • C. 

      Net charge on the protein

    • D. 

      A, b, and c

    • E. 

      B and c

  • 40. 
    A stain that does not interact with proteins in SDS-PAGE staining process and refrred to as negative stain. Which of the following stain show this characteristic? it is 
    • A. 

      Silver stain

    • B. 

      Copper stain

    • C. 

      Coomassie blue stain

    • D. 

      None

  • 41. 
    SDS-Page provides information on all of the following EXCEPT
    • A. 

      Charge on subunit

    • B. 

      Number and size of subunits

    • C. 

      Purity

    • D. 

      Molecular weight

  • 42. 
    Smaller proteins will have a ______Rf value while larger proteins will have a _____Rf value during gel electrophoresis
    • A. 

      Smaller, larger

    • B. 

      Cannot be estimated

    • C. 

      Larger, smaller

  • 43. 
    Assume that you are separating a protein with MW of approximately 45,000Da along with MW standard ranging from 6,500 to 66,200 Da using SDS-PAGE. Which percent of gel would you use for this sample? 
    • A. 

      4%

    • B. 

      25%

    • C. 

      12%

    • D. 

      7.5%

  • 44. 
    Polyacrylamide gels are prepared by polymerization of acrylamide monomer and N-N'-methylene-bis-acrylamide cross-linker in the presence of: 
    • A. 

      TEMED + b- mercaptoethaol

    • B. 

      APS + b- mercaptoethaol

    • C. 

      APS + TEMED

    • D. 

      Tris- buffer + phosphate ion

  • 45. 
    Which type of gel separate proteins based on charge: mass ratio? 
    • A. 

      Native gel

    • B. 

      2-D electrophoresis

    • C. 

      Centrifugation

    • D. 

      SDS-PAGE

  • 46. 
    SDS binds to hydrophobic regions of the denatured protein chain in a constant ratio of: 
    • A. 

      2g SDS per gram protein

    • B. 

      1 g SDS per gram protein

    • C. 

      1 g SDS per 1.4 g protein

    • D. 

      1.4 g SDS per gram protein

  • 47. 
    In Western blot analysis, you used TMB (3'3'5,5'-Tetramethyl Benzidine) as a last step for visualizing unkonwn protein (ovalbumin). What is TMB? 
    • A. 

      A chromogenic substrate

    • B. 

      An enzyme

    • C. 

      Secondary antibody

    • D. 

      Primary antibody

  • 48. 
    Proteins that are separted in SDS-PAGE are subjected to treat with all of the following reagents/factor EXCEPT: 
    • A. 

      Tris-buffer

    • B. 

      Ammonim (APS)

    • C. 

      B-Mercatoethanol

    • D. 

      SDS

    • E. 

      Heat

  • 49. 
    Which of the following statement is NOT true for indirect method of protein detection of Western blot? 
    • A. 

      A wide variety of labeled secondary antibodies are available commercially

    • B. 

      Immunoreactivity of primary antibody may be reduced as result of labeling

    • C. 

      Same labeled secondary antibody can be used for detection, it is versatile

    • D. 

      Immunoreactivity of the primary antibody is not affected by labeling

    • E. 

      Different visualization markers can be used with the same primary antibody

  • 50. 
    Cholesterol can easily be metabilized to CO2 and H2O in humans and excreted 
    • A. 

      False

    • B. 

      True

  • 51. 
    Which of the follwing is the caharacteristic (s) of pH curve in enzyme kinetic analysis? 
    • A. 

      Rectangular

    • B. 

      Sigmoidal

    • C. 

      Hyperbolic

    • D. 

      Linear

    • E. 

      Bell shape

  • 52. 
    A prosthetic group 
    • A. 

      Is composed of polypeptides

    • B. 

      Does not participate in chemical reactions

    • C. 

      Is a tightly bound nonprotein part of an enzyme

    • D. 

      Is present in all enzymes

    • E. 

      Is a nonprotein enzyme

  • 53. 
    Most of your blood cholesterol is produced by: 
    • A. 

      Pancreas

    • B. 

      Heart

    • C. 

      Liver

    • D. 

      Kidney

  • 54. 
    For noncompetitive inhibiton the apparent Vmax is larger than Vmax by a factor of (1 + [ I ]/k )
    • A. 

      True

    • B. 

      False

  • 55. 
    CHolesterol is synthesized from 
    • A. 

      Choline

    • B. 

      Lipoic acid

    • C. 

      Acetyl CoA

    • D. 

      Malic acid

  • 56. 
    Which of the following binds plasma cholesterol and transport cholesterol to the liver? 
    • A. 

      LDL

    • B. 

      Chylomicrons

    • C. 

      HDL

    • D. 

      VLDL

  • 57. 
    Which of the following serves as a substrate for Acid phosphatase? 
    • A. 

      PNPP

    • B. 

      PNP

    • C. 

      KOH

    • D. 

      Cell wall

  • 58. 
    Which of the follwing is defined as the "turnover number for an enzyme?"
    • A. 

      Kcat/km

    • B. 

      K1

    • C. 

      (k-1+kcat)/k1

    • D. 

      Kcat

    • E. 

      K-1

  • 59. 
    A Lineweaver-burk (double reciprocal) analysis allows for the determination of: 
    • A. 

      Km only

    • B. 

      Vmax only

    • C. 

      Km and Vmax

    • D. 

      The reaction product

    • E. 

      None is true

  • 60. 
    All of the follwing chemicals are the compopnents of transfer buffer except
    • A. 

      Methanol

    • B. 

      Tris-buffer

    • C. 

      SDS

    • D. 

      Glycine

  • 61. 
    A 0.2 ml pure Muramidase (2.5 mg/ml) hydrolyzed 0.2 mmol of cell wall in 5 minutes. What is the specific activity
    • A. 

      40 micromol/min/mg

    • B. 

      0.04 millimol/min/mg

    • C. 

      80 micromol/min/mg

    • D. 

      None

  • 62. 
    Lysozyme hydrolyses
    • A. 

      Disulfide bond

    • B. 

      Phosphodiester bond

    • C. 

      Hydrogen bond

    • D. 

      Glycosidic bond

  • 63. 
    During acid phosphatase kinetic analysis, which one of the follwing was used as a substare? 
    • A. 

      NaCl

    • B. 

      Bacterial cell wall

    • C. 

      PNPP

    • D. 

      Muramic acid

  • 64. 
    Which one of the following does not apply to Michaelis-Menten assumptions: 
    • A. 

      The E, S, and ES are in rapid equilibrium

    • B. 

      The product formation is inversely proportional to ES complex concentration

    • C. 

      The product formation is directly proportional to ES complex concentration

  • 65. 
    Which statement is true for an enzyme catalyzed reaction if [S] >> km 
    • A. 

      The enzyme activity in the linear range

    • B. 

      The enzyme is saturated with substrate

    • C. 

      The enzyme activity is half of the maximal rate

    • D. 

      The enzyme is showing first order of reaction

  • 66. 
    Following are the properties of Lysozyme except:
    • A. 

      Has MW of 14,000 dalton

    • B. 

      Works on Micrococcus lysodeikticus cell wall

    • C. 

      Hydrolyses phosphodiester bond

    • D. 

      Provides defense mechanism against bacterial infection

    • E. 

      Rich in tears

  • 67. 
    One international unit of an enzyme is defined as the amount that catalyzes: 
    • A. 

      The formation of one millimol of product in one min

    • B. 

      The formation of one micromol of product in one min

    • C. 

      The formation of one mol of product in one min

    • D. 

      The formation of one micromol of product in one hour

  • 68. 
    Which of the follwing related to the mchanism of enzymatic reaction 
    • A. 

      Free energy of activation increases

    • B. 

      The energy of activation increases

    • C. 

      Enzymes change the equilibrium constants of the reaction

    • D. 

      Enzymes decrease the energy of activation

    • E. 

      Enzymes have no effect in enzyme catalyzed reaction

  • 69. 
    Which of the following is the proper component sequence in western blotting
    • A. 

      Fiber pad, filter paper, nitrocellulose membrane, gel filter paper, fiber pad

    • B. 

      Fiber pad, nitrocellulose membrane, filter paper, gel, filter paper, fiber pad

    • C. 

      Fiber pad, filter paper, gel, nitrocelluloes membrane, filter paper, fiber pad

    • D. 

      Fiber pad, nitrocellulose membrane, filter paper, gel, filter paper, fiber pad

  • 70. 
    Name the chemical which is extremely toxic in gel electrophoresis, causing central nervous system paralysis upon absorbing through skin 
    • A. 

      Ammonium persulfate

    • B. 

      Acrylamide

    • C. 

      TEMED

    • D. 

      SDS

  • 71. 
    Sodium dodecyl sulfate gel electrophoresis is often used for: (check all that apply) 
    • A. 

      Determination of MW of proteins

    • B. 

      Protein purification

    • C. 

      Determination of protein sedimentation constants

    • D. 

      All of the above

    • E. 

      A and c

  • 72. 
    Which one of the follwing is not used as a blocking reagent in western blot? 
    • A. 

      Gelatin

    • B. 

      BSA

    • C. 

      Colloidal reagent

    • D. 

      Skim milk

  • 73. 
    What is the function of the "gel" in many electrophoresis procedures? 
    • A. 

      Serves as an electrical conductor

    • B. 

      Contributes physically to the separation of proteins

    • C. 

      B and c

    • D. 

      A and b

  • 74. 
    A catalytically inactive protein formed by removal of the cofactor from an active enzyme is referred to as: 
    • A. 

      Apoenzyme

    • B. 

      Prosthetic group

    • C. 

      Coenzyme

    • D. 

      Holoenzyme

  • 75. 
    Factors affecting the velocity of enzyme catalyzed reaction are: 
    • A. 

      Enzyme concentration only

    • B. 

      Substrate concentration

    • C. 

      PH only

    • D. 

      Temperature only

    • E. 

      All of the above

  • 76. 
    Separation of proteins by SDS-electrophoreiss takes adavantage of differences in: 
    • A. 

      Amino acid composition of proteins

    • B. 

      Protein isoelectric points

    • C. 

      Protein size

    • D. 

      Protein shape

    • E. 

      Protein solubility

  • 77. 
    What will be the initial velocity for an enzyme that has Km= 3S
    • A. 

      50% of Vmax

    • B. 

      25% of Vmax

    • C. 

      75% of Vmax

    • D. 

      Vmax