Enzymes and Kinetics

Q1: Which of the following common drugs is not a specific enzyme inhibitor?

A Iodine

B Methotrexate

C Sulfbnilamide

D Penicillin

Q2: The effect of non-competitive inhibition on a Lineweaver-Burk Plot is that

A it can move the entire curve to the right

B it can change the y-intercept

C it can change the x-intercept

D all of these

Q3: Which of the following activity is possible by transferases?

A Transfer of methyl groups

B Transfer of glycosyl group

C Both (a) and (b)

D None of these

Q4: The conformational change in an enzyme after the substrate is bound that allows the chemical reaction to proceed, can be explained by

A induced fit

B transition

C fit and fine

D Pasteur

Q5: Given an enzyme with a Km = 10m M and Vmax = 100 m mol/min. If [S] = 100 m M, which of the following will be true?

A A 10 fold increase in Vmax would increase velocity 10 fold y

B A 10 fold decrease in Km would increase velocity

C Both (a) and (b)

D A 10 fold increase in Vmax would decrease velocity 20 fold

Q6: In competitive inhibition a factor is obtained from the measurement of

A Vmax

B KM

C Y-intercept in Lineweaver-Burk Plot

D None of these

Q7: The types of inhibition pattern based on Michaelis Menten equation are

A competitive

B non-competitive

C uncompetitive

D all of the above

Q8: A competitive inhibitor of an enzyme is usually

A a highly reactive compound

B a metal ion such as Hg2+ or Pb2+

C structurally similar to the substrate.

D water insoluble

Q9: The plot commonly used for determining the value of Vmax is

A Lineweaver Burk plot

B Langmuir plot

C Eadie Hofstee plot

D all of these

Q10: The rate-determining step of Michaelis Menten kinetics is

A the complex formation step

B the complex dissociation step to produce product

C the product formation step

D Both (a)and(c)

Q11: An allosteric inhibitor of an enzyme usually

A participates in feedback regulation

B denatures the enzyme

C is a hydrophobic compound

D causes the enzyme to work faster

Q12: An enzyme and a reactant molecule maintain relationship as

A a temporary association

B an association stabilized by a covalent bond

C one in which the enzyme is changed permanently

D non complementary binding

Q13: Non-competitive inhibitor of an enzyme catalyzed reaction

A decreases Vmax

B binds to Michaelis complex (ES)

C both (a) and (b)

D can actually increase reaction velocity in rare cases

Q14: Which category of enzymes belongs to class two in the international classification?

A Hydrolases

B Ligases

C Transferases

D Isomerase

Q15: Which graphical method is used to determine an enzyme degrey?e of cooperativit

A Hill plot

B Koshland curve

C Michaelis-Menten hyperbola

D Can not be determined

Q16: The types of inhibition pattern based on Michaelis Menten equation are

A competitive

B non-competitive

C uncompetitive

D all of the above

Q17: A classical uncompetitive inhibitor is a compound that binds

A reversibly to the enzyme substrate complex yielding an inactive ESI complex

B irreversibly to the enzyme substrate complex yielding an inactive ESI complex

C reversibly to the enzyme substrate complex yielding an active ESI complex

D irreversibly to the enzyme substrate complex yielding an active ESI complex

Q18: An enzyme is assayed at an initial substrate concentration of 2 x 10-5M. In 6 minute, half of the substrate is used. The Km for the substrate is 2 x 10-3M. The value of k in minute is

A 0.115

B 0.42

C 0.093

D 6.693

Q19: The Woolf-Augusteinsson-Hofstee plot of ν versus ν/[S] and the Eadie-Scatchard plot of ν/[S] versus ν do not involve reciprocals of ν therefore are considered to be more reliable when the error in v is

A non-significant

B significant

C nothing to do with the reliability

D non significant in selected cases

Q20: Which of these enzymes contains a Zinc (Zn) ion?

A Carboxypeptidase A

B Phosphorylase B kinase

C Tyrosine hydroxylase

D Phosphodiesterase

Q21: Which of these proteases is not a cysteine active site protease?

A Calpain

B Cathepsin D

C Papain

D None of the above

Q22: The active site of an enzyme remains

A at the center of globular proteins

B rigid and does not change shape

C complementary to the rest of the molecule

D none of the above

Q23: The relationship between KeqKm and Vmax is known as

A Haldane equation

B Michaelis Menten equation

C Numerical solution approach

D Gibbs-Helmholtz equation

Q24: Which of the following statements is not true?

A Enzymes are proteins that bind to specific substrates and increase the velocity of reactions involving those substrates

B Enzymes function by overcoming the activation energy barrier of a reaction

C Enzymes make thermodynamically favorable reactions to proceed; they cannot make unfavorable reactions to occur

D Enzymes only function when they are in intact cells

Q25: Which of the following statements is true for enzymatically catalyzed reaction?

A The activation energy of the reaction is lowered so that a larger proportion of the substrate qualifies to overcome it

B Additional substrate molecules are energized to overcome the activation energy of the reaction

C The activation energy of the reaction is increased, thus decreasing the likelihood that any substrate molecules will overcome it

D The activation energy of the reaction is lowered so that a fewer substrate molecules can overcome it

Q26: Linear inhibition is sometimes called as

A complete inhibition

B incomplete inhibtion

C partial inhibition

D mixed inhibition

Q27: In a Lineweaver-Burk Plot, competitive inhibitor shows which of the following effect?

A It moves the entire curve to right

B It moves the entire curve to left

C It changes the x-intercept

D It has no effect on the slope

Q28: A noncompetitive inhibitor of an enzyme-catalyzed reaction

A increases KM and increases Vmax

B increases KM and reduces Vmax

C reduces KM and increases Vmax

D reduces KM and reduces Vmax

Q29: The enzyme inhibition can occur by

A reversible inhibitors

B irreversible inhibitors

C Both (a) and (b)

D None of these

Q30: The active site of an enzyme remains

A at the center of globular proteins

B rigid and does not change shape

C complementary to the rest of the molecule

D none of the above

Q31: Quasi steady state is also known as

A Michaelis Menten approach

B Briggs-Haldane approach

C Pseudo steady state

D all of the above

Q32: In competitive inhibition a factor is obtained from the measurement of

A Vmax

B KM

C Y-intercept in Lineweaver-Burk Plot

D None of these

Q33: The conformational change in an enzyme after the substrate is bound that allows the chemical reaction to proceed, can be explained by

A induced fit

B transition

C fit and fine

D Pasteur

Q34: The reciprocal equation for non competitive inhibition can be arranged to the equation for the

A Dixon plot

B Woolf-Augusteinsson-Hofstee plot

C Eadie-Scatchard plot

D Hanes-Woolf plot


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