quiz1pracs05

quiz1pracs05 - MIT Department of Biology 7.013 Introductory...

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MIT Department of Biology 7.013: Introductory Biology - Spring 2005 Instructors: Professor Hazel Sive, Professor Tyler Jacks, Dr. Claudette Gardel 7.013 Spring 2005 Practice Quiz 1 7.013 Practice Quiz 1
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7.013 Spring 2005 Practice Quiz 1 Question 1 Shown below is a close up of a substrate (UDP-Glucose) bound to the active site of an enzyme (UTase). The shaded area is the enzyme; the structure of the substrate is shown. CH 2 OH Ser161 NH 2 H O H H N OH H OH H O H H O O O P O O O P H H CH 2 O O H H N H O OH OH Arg 31 l Two amino acids of the enzyme are high ighted: Arg 31 and Ser 161. a) Part (I) of the figure below shows the relative positions of Arg 31 and the portion of i the substrate with wh ch it interacts; part (II) shows the structure of arginine. (I) O O O P O P O NH (II) H O O H CC H 2 CH 2 CH 2 N C NH 2 Arg 31 O C Arginine NH 2 The side chain of Arg 31 interacts with the portion of the substrate shown above. What type of interaction(s) is/are possible between the side chain of Arg 31 and this portion of the substrate? (Circle all that apply.) hydrophobic Hydrogen Ionic van der Waals interaction bond bond interaction
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7.013 Spring 2005 Practice Quiz 1 b) The figure below shows the relative positions of Ser 161 and the portion of the substrate with which it interacts (I) ; (II) shows the structure of serine. (I) Ser161 () II NH O O H CC H 2 OH P O P O C Serine O O O O The side chain of Ser 161 interacts with the portion of the substrate shown above. What type of interaction(s) is/are possible between the side chain of Ser 161 and this portion of the substrate? (Circle all that apply.) hydrophobic Hydrogen Ionic van der Waals interaction bond bond interaction c) Suppose that you are studying the interactions between the substrate and the enzyme. It is possible to make variant enzymes that differ from the one above by a single amino acid substitution. (For example, Asp 78 could be replaced with tryptophan). You could use this technique to investigate the roles of each amino acid shown above. If you change Arg 31 to a lysine, would you predict that the substrate still binds, or that the substrate now fails to bind to the altered enzyme? Explain.
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7.013 Spring 2005 Practice Quiz 1 Question 2 a) You have started a UROP in the behavioral genetics department at the University of Monterrey in Mexico. For your first assignment, your advisor asks you to figure out the genetics of a particular species of honeybee that has just been discovered- a red killer bee! To begin your studies, you cross this true breeding red killer bee with the local true breeding blue gentle bee. The F1 progeny show the following phenotype: 54 red "feisty" bees You have characterized the disposition as such: gentle: will ignore humans and simply gather pollen killer: will attack and sting without provocation feisty: will approach humans threateningly, but will not sting a) Write the genotypes of the P parental types and the F1 progeny . (Be sure to indicate which particular phenotype corresponds to each parental genotype.)
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quiz1pracs05 - MIT Department of Biology 7.013 Introductory...

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