Quiz
Enzymes
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Questions in this quiz (12)
11- which is true for a denatured enzyme ;
- Aa) it looses its native conformation
- Bb) its peptide bond are broken
- Cc) enzyme solubility increases
- Dd) it can still binds its substrate and catalyze the reaction
22- initial velocity of an enzyme - catalyzed reaction is which ;
- Aa) velocity before adding the enzyme
- Bb) velocity before accumulation of product
- Cc) velocity at zero substrate concentration
- Dd) velocity with substrate concentration equal to Km
- Ee) the lowest velocity
33- a non competitive inhibitor of an enzyme ;
- Aa) increase km with no change in Vmax
- Bb) decrease km and Vmax
- Cc) increase Vmax with no change in km
- Dd) decrease Vmax with no change in km
44- a coenzyme is which of the following ;
- Aa) the protein part of an enzyme
- Bb) an inactive enzyme
- Cc) an inorganic cofactor
- Dd) a substrate needed for the enzyme action
55- an enzyme catalyzes reaction by which of the following mechanism ;
- Aa) forcing the reaction against natural equilibrium
- Bb) lowering the activation energy of the reaction
- Cc) binding the products of the reaction to guarantee its continuity
- Dd) giving the reactants energy required to make the reaction
66- Michaelis constant equals which of the following ;
- Aa) half the substrate concentration that gives Vmax
- Bb) the substrate concentration that half saturate the enzyme
- Cc) the initial velocity at half saturation of the enzyme
- Dd) none of the above
77- the effect of methotrexate on dihydrofolate reductase is ;
- Aa) increased km with no change in Vmax
- Bb) decreased km and Vmax
- Cc) no change in km and decreased Vmax
- Dincreased km and decreased Vmax
88-what is meant by induction of an enzyme ;
- Aa) increased synthesizes of the enzyme from the gene
- Bb) increased kinetic energy of the enzyme
- Cc) activation of an inactive enzyme
- Dd) enhanced affinity between the enzyme and its substrate
99- the effect of allopurinole on xanthine oxidase enzyme ;
- Aa) decrease formation of uric acid
- Bb) decreases Vmax and no change in km
- Cc) the effect can not be reversed by dialysis
- Dd) the effect can not be reversed by increasing substrate concentration
- Ee) all of the above
1010- an allosteric molecule is characterized by ;
- Aa) can bind covalently to the enzyme
- Bb) can bind to the active site of the enzyme
- Cc) binds non covalently to the enzyme
- Dd) is derived from a vitamine
1111-which of the following doesn't bind to the active site of the enzyme ;
- Aa) the substrate
- Bb) the competitive enzyme
- Cc) the coenzynme
- Dd) the allosteric molecule
- Ee) none of the above
1212-digestive enzyme belong to the class of ;
- Aa) hydrolyases
- Bb) ligases
- Cc) lyases
- Dd) transferases
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- medicate and innovate ( for service the medical student) group
- Author
- Nada Medhat
- Language
- English
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