BIBC 102 SS2 Practice Exam Version 1.0 KEY

BIBC 102 SS2 Practice Exam Version 1.0 KEY - BIBC 102...

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BIBC 102 Practice Exam v 1.0 Dedicated to Dr. Aaron Coleman Lkklkkkkkkkkkkl; b. Fill in the following table about the amino acids Serine and Cysteine. Property Serine Cysteine Classification Polar, uncharged Polar, uncharged Level(s) of protein structure the side chain can potentially be involved in. Tertiary, Quaternary Tertiary, Quaternary Present in TPI? (Yes/No) No No Present in Chymotrypsin (Yes/No) Yes No c. Circle the amino acid side chain (R group) that could receive a phosphate group from a protein kinase. d. What are the three amino acids that can be phosphorylated? Serine, Threonine Usually for Enzyme regulation Tyrosine Usually for signal transduction of extracellular signals 2. The equilibrium constant (Keq) is much greater than 1. a. What sign is the G‟ o
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BIBC 102 Practice Exam v 1.0 Dedicated to Dr. Aaron Coleman Negative G‟ o b. Is this reaction endergonic? No, this is exergonic. c. Is the reverse reaction favorable? If it isn‟t under what conditions would it be favorable? No. If the product concentrations are sufficiently high and the G‟ o is sufficiently low, 10kJ/mol. d. How would a catalyst affect the equilibrium constant and the reaction? How would it accomplish this? The equilibrium constant would be unchanged but would increase the rate of the forward and reverse reactions. It will accomplish this by: 1. The enzyme will increase the substrate/intermediate enthalpy (H) by straining the bonds of the substrate, and thereby will decrease the enthalpy of activation (H o++ . 2. The enzyme will decrease the entropy of the substrate by holding it in a precise orientation, which will make the entropy of activation (S o++ ) less negative. 3. How do exergonic reactions actually power endergonic reactions in the body? Use the example of Glutamine biosynthesis in your response. Chemical reactions can be physically linked and as a result their free energy changes will become additive. In the case of Glutamine biosynthesis, the synthesis of Glutamine from its precursors has a G‟ o of + 24.5 kJ/mol and is thus endergonic. The hydrolysis of ATP has a G‟ o of -30.5 kJ/mol and is thus highly exergonic. By linking the two reactions together we create a spontaneous reaction that passes through a high energy Acyl Phosphate intermediate.
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BIBC 102 Practice Exam v 1.0 Dedicated to Dr. Aaron Coleman 4. Draw the mechanism for Triose Phosphate Isomerase with all proton and electron pushing arrows. Then construct a free energy diagram of the enzyme catalyzed reaction, with and without the lid loop.
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BIBC 102 Practice Exam v 1.0 Dedicated to Dr. Aaron Coleman 5. Chymotrypsin is a very well studied proteolytic enzyme. Answer the following questions about Chymotrypsin. a. Chymotrypsin is synthesized in an inactive form and then activated by proteolysis
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This note was uploaded on 09/20/2011 for the course BIBC 102 taught by Professor Price during the Summer '02 term at UCSD.

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BIBC 102 SS2 Practice Exam Version 1.0 KEY - BIBC 102...

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