biochem2exam2008withoutanswers

biochem2exam2008withoutanswers - Name (Print Last, First)_...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Name ( Print Last, First )__________________________________________________ SECOND EXAMINATION Biology 366 and Chemistry 361/461 March 18, 2008 INSTRUCTIONS : 1) You are responsible for printing your name legibly at the top of this page. 2) You must use a number two pencil to enter your answers in the scantron . 3) Make sure that the I.D. number, name (last and first) and test form (use form A) fields are properly filled. The I.D. number field should contain ten digits - you may choose a variation of your Student’s ID number, SSN or phone number starting with the area code. 4) At the end of the test , insert the scantron inside the examination, and return both to the proctor. Actual Score Maximum Multiple Choice 100 Adjusted Score (if applicable) 100 Mean ± SD Exam Grade 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
MULTIPLE CHOICE QUESTIONS (40 questions total; 2.5 points each) SELECT THE MOST CORRECT ANSWER FOR EACH MULTIPLE-CHOICE QUESTION For questions 1 through 3 below, consider the following data for the Lineweaver-Burk plots obtained for a homodimeric enzyme with a molecular weight of 20,000 D. At an enzyme concentration of 1.0 mg/mL, the plots intercepted the x-axis at –2.0 mM -1 and -4.0 mM -1 and showed two y-intercepts at 6.0 x 10 -4 mM -1 .sec and 1.2 x 10 -3 mM -1 .sec in the absence and presence of 0.040 mM of an inhibitor. 1. What type of inhibitor is present? A) A competitive inhibitor. B) A non-competitive inhibitor. C) An uncompetitive inhibitor. D) An allosteric inhibitor. E) An affinity label. 2. The values of K M and V max are, respectively, A) 0.50 mM -1 ; 1.7 x 10 -4 M -1 .sec -1 B) 2.5 x 10 -4 M -1 ; 1.7 mM -1 .min C) -0.50 mM; 8.3 x 10 -4 M -1 .sec D) 0.50 mM; 1.0 x 10 2 M.min -1 E) 0.040 mM; 6.0 x 10 -4 mM -1 .sec 3. The values of K I and k cat are, respectively, A) 0.040 mM; 6.0 x 10 7 hr -1 B) 0.010 mM -1 ; 1.0 x 10 4 M.min -1 C) -0.080 mM -1 ; 0.5 min -1 D) 2.0 x 10 -2 M; 2.0 min -1 E) 0.080 mM; 6.0 x 10 -4 mM.mL.mg -1 .sec -1 4. What is the relationship between [S] and K M when an enzyme-catalyzed reaction proceeds at 25% V max ? A) [S] = 0.25 K M B) [S] = 0.33 K M C) [S] = 0.50 K M D) [S] = 1.0 K M E) [S] = 1.33 K M 5. The free energy change for an uncatalyzed forward reaction is -20 kcal mol -1 whereas the activation energy for the corresponding catalyzed backward reaction is +25 kcal mol -1 . Assuming that the enzyme stabilizes the energy of the transition state by one-half, the binding energy, the free energy change for the uncatalyzed backward reaction and the activation energy for the uncatalyzed forward reaction are (in kcal mol -1 ), respectively, A) +5; -20; +45 B) -5; +20; +10 C) +2.5; -25; +5 D) -2.5; +30; 0 E) +5; -20; +15 6. The efficiency of an enzyme is best characterized by its value of A) V o B) V max C) K M D) k cat E) k cat /K M 7. The active site region of an enzyme usually includes only 5-10% of the amino acids in the enzyme. The function of the other 90-95% of the amino acids is to
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/26/2008 for the course CHEM 361 taught by Professor Defreitas during the Spring '08 term at Loyola Chicago.

Page1 / 7

biochem2exam2008withoutanswers - Name (Print Last, First)_...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online