5865474
Description
Quiz by Nada Medhat, updated more than 1 year ago
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Created by Nada Medhat
over 8 years ago
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Question 1
Question
1- which is true for a denatured enzyme ;
Answer
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a) it looses its native conformation
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b) its peptide bond are broken
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c) enzyme solubility increases
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d) it can still binds its substrate and catalyze the reaction
Question 2
Question
2- initial velocity of an enzyme - catalyzed reaction is which ;
Answer
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a) velocity before adding the enzyme
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b) velocity before accumulation of product
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c) velocity at zero substrate concentration
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d) velocity with substrate concentration equal to Km
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e) the lowest velocity
Question 3
Question
3- a non competitive inhibitor of an enzyme ;
Answer
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a) increase km with no change in Vmax
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b) decrease km and Vmax
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c) increase Vmax with no change in km
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d) decrease Vmax with no change in km
Question 4
Question
4- a coenzyme is which of the following ;
Answer
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a) the protein part of an enzyme
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b) an inactive enzyme
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c) an inorganic cofactor
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d) a substrate needed for the enzyme action
Question 5
Question
5- an enzyme catalyzes reaction by which of the following mechanism ;
Answer
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a) forcing the reaction against natural equilibrium
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b) lowering the activation energy of the reaction
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c) binding the products of the reaction to guarantee its continuity
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d) giving the reactants energy required to make the reaction
Question 6
Question
6- Michaelis constant equals which of the following ;
Answer
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a) half the substrate concentration that gives Vmax
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b) the substrate concentration that half saturate the enzyme
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c) the initial velocity at half saturation of the enzyme
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d) none of the above
Question 7
Question
7- the effect of methotrexate on dihydrofolate reductase is ;
Answer
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a) increased km with no change in Vmax
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b) decreased km and Vmax
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c) no change in km and decreased Vmax
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increased km and decreased Vmax
Question 8
Question
8-what is meant by induction of an enzyme ;
Answer
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a) increased synthesizes of the enzyme from the gene
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b) increased kinetic energy of the enzyme
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c) activation of an inactive enzyme
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d) enhanced affinity between the enzyme and its substrate
Question 9
Question
9- the effect of allopurinole on xanthine oxidase enzyme ;
Answer
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a) decrease formation of uric acid
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b) decreases Vmax and no change in km
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c) the effect can not be reversed by dialysis
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d) the effect can not be reversed by increasing substrate concentration
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e) all of the above
Question 10
Question
10- an allosteric molecule is characterized by ;
Answer
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a) can bind covalently to the enzyme
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b) can bind to the active site of the enzyme
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c) binds non covalently to the enzyme
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d) is derived from a vitamine
Question 11
Question
11-which of the following doesn't bind to the active site of the enzyme ;
Answer
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a) the substrate
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b) the competitive enzyme
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c) the coenzynme
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d) the allosteric molecule
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e) none of the above
Question 12
Question
12-digestive enzyme belong to the class of ;
Answer
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a) hydrolyases
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b) ligases
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c) lyases
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d) transferases
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