47. Enzymes work by a. raising the activation energy of a reaction and thus spee
ID: 37275 • Letter: 4
Question
47. Enzymes work by
a. raising the activation energy of a reaction and thus speeding up the reaction.
b. lowering the activation energy of a reaction and thus speeding up the reaction
c. raising the ?G of a reaction and thus speeding up the reaction
d. lowering the ?G of a reaction and thus speeding up the reaction
e. changing the free energy of the products and speeding up the reaction
48. A reaction involving the loss of one or more electrons
a. oxidation
b. reduction
c. electronegativity
d. free energy (?G)
e. none of the above
49. Glycolysis occurs in the ________; the Krebs (TCA) cycle occurs in the ______ of eukaryotes and the ______ of microbes.
a. cytoplasm, cytoplasm, cytoplasm
b. mitochondria, cytoplasm, mitochondria
c. cytoplasm, mitochondria, cytoplasm
d. cytoplasm, photosynthesis, cytoplasm
e. cytoplasm, mitochondria, mitochondria
50. A reaction involving the gain of one or more electrons is a(n) _________ reaction.
a. oxidation
b. reduction
c. catabolic
d. buffered
e. None of these are correct.
51. Which property below is not a characteristic of enzymes?
a. They are required only in large amounts.
b. They can be altered reversibly during a reaction. c. They do not alter the ?G of a reaction.
d. They are used over and over again.
e. Most are proteins.
52. Enzymes work by
a. raising the activation energy of a reaction and thus speeding up the reaction.
b. lowering the activation energy of a reaction and thus speeding up the reaction.
c. raising the ?G of a reaction and thus speeding up the reaction.
d. lowering the ?G of a reaction and thus speeding up the reaction.
e. changing the free energy of the products and speeding up the reaction.
53. What kind of interaction is not involved in the binding of a substrate to a normally functioning enzyme?
a. H bonds
b. a transient covalent bond
c. ionic bonds
d. a permanent covalent bond
e. hydrophobic interactions
54. Enzymes greatly decrease the activation energy. Which one of the following mechanisms does NOT explain how this might happen.
a. By providing a binding site (the active site) for the substrate(s), the enzyme can concentrate the reactants locally.
b. One or more covalent bonds within the enzyme are broken which ultimately provide the energy to convert the reactants to products.
c. The active site can strain a bond that is supposed to be broken and/or orient substrates properly to facilitate the reaction.
d. Reactive groups on the enzyme can also enhance the probability that the reaction will occur.
e. Transient covalent bonds or other strong interactions can also occur.
55. What kind of enzyme adds phosphate groups to enzymes for the purpose of activating or deactivating them?
a. phosphatases
b. protein kinases
c. flippases
d. glycosyltransferases
e. carboxypeptidase
Explanation / Answer
47. b. lowering the activation energy of a reaction and thus speeding up the reaction
48. a. oxidation
49. e. cytoplasm, mitochondria, mitochondria
50. b. reduction
51. b. They can be altered reversibly during a reaction.
52. b. lowering the activation energy of a reaction and thus speeding up the reaction.
53. d.a permanent covalent bond
54. b. One or more covalent bonds within the enzyme are broken which ultimately provide the energy to convert the reactants to products.
55. b. protein kinases
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