Chap20 Enzymes and vitamins

Chap20 Enzymes and vitamins - Chapter 20 Enzymes and...

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Chapter 20 Enzymes and Vitamins 20.1 Multiple - Choice Questions 1) To what main class of enzymes does the enzyme that catalyzes the conversion of lactose to galactose and glucose belong? A) oxidoreductase B) transferase C) hydrolase D) lyase E) isomerase Answer: C 2) To what main class of enzymes does the enzyme that catalyzes the following reaction belong? O OH CH3 C COO - CH3 C HCOOA) oxidoreductase B) transferase C) hydrolase D) lyase E) isomerase Answer: A 3) To what main class of enzymes does the enzyme that catalyzes the following reaction belong? ser - ala ser + ala A) oxidoreductase B) transferase C) hydrolase D) lyase E) isomerase Answer: C 4) Compared to an uncatalyzed reaction, an enzyme - catalyzed reaction A) uses less substrate. B) produces different products. C) occurs at a faster rate. D) requires more energy. E) requires a higher temperature. Answer: C 5) Which of the following is NOT a step in the enzyme - catalyzed conversion of a substrate to product? A) The substrate changes its shape so it can bind at the active site. B) The substrate binds in the active site to form the E - S complex. C) The enzyme assists in the conversion of the substrate to product. D) The product is released from the active site. E) A new substrate molecule binds to the enzyme for a new cycle Answer: A Page 271 6) The formation of an enzyme - substrate complex is the ________ step in enzyme action. A) first B) second C) third D) fourth E) last Answer: A 7) The active site of an enzyme A) is remote from the site of substrate attachment. B) is converted to a product. C) catalyzes the reaction. D) increases the energy of reaction.
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E) includes the entire enzyme. Answer: C 8) The water - soluble B and C vitamins supply A) essential amino acids. B) substrates necessary for most of the reactions in the body. C) essential fatty acids. D) coenzymes required by some enzymes. E) competitive inhibitors needed to regulate enzyme activity. Answer: D 9) The optimum temperature for sucrase activity is 37°C. The hydrolysis of sucrose is slowest at which temperature in the choices below? A) 0°C B) 10°C C) 20°C D) 25°C E) 45°C Answer: A 10) Which of the following is NOT true for a competitive inhibitor? A) It occupies the active site. B) It cannot be converted to products. C) It has a structure similar to the substrate. D) Increasing the substrate concentration can reverse competitive inhibition. E) It binds to the enzyme at a site remote from the active site. Answer: E 11) A noncompetitive inhibitor A) binds at the active site of the enzyme. B) alters the three - dimensional structure of the enzyme. C) increases the rate of the enzyme - catalyzed reaction. D) has a structure similar to the substrate. E) has its effect reversed by adding more substrate.
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This note was uploaded on 12/18/2011 for the course CHEMISTRY 0012 taught by Professor Wester during the Fall '10 term at St. Thomas FL.

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Chap20 Enzymes and vitamins - Chapter 20 Enzymes and...

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