CH369 exam3s04 - Written Answers 1 The compound 3-5 cyclic...

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Written Answers 1. The compound 3’-5’ cyclic AMP has been described as the “second” messenger for control of carbohydrate metabolism. a) Draw the structure of 3’-5’ cyclic AMP. (2 points) b) Give the name of one “first” messenger (hormone) for control of carbohydrate metabolism: (2 points) any one of epinephrine (adrenaline), glucagon, insulin c) The activation of glycogen breakdown involves a series of reactions (a cascade) in which there is a very large amplification of the original hormonal signal. In very simple terms describe why there is a very non-linear response to the original signal rather than a 1:1 relationship between the amount of hormone arriving at the cell and the amount of glycogen degraded. A diagram of the cascade is not sufficient.(5 points) Several of the steps of the cascade involve the activation of enzymes that can serve to catalyze the activation of components further along in the cascade pathway. Because one enzyme molecule can activate not one, but many substrate molecules (i.e. the next component) the process is highly non-linear. A diagram illustrating this (not required) is Activating Enzyme ( 1 molecule) 1000’s of 1000’s next component _____________________________________ next component (inactive) (active)
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2. The following diagram represents the breakdown of pyruvate through the citric acid cycle. Answer the following 10 questions regarding this process. Each question is worth 1 point, there can be more than 1 response to each question and the grading is all-or-none for each question. (1) At which step(s) is FAD involved _ 1, 7, 9 __ (2) At which step(s) is CO 2 evolved __ 6, 7 ___ (3) At which step(s) is NADH produced ___ 5, 7, 11 __ (4) What is the name of the product produced in Step 9 ____ fumarate ______ (5) What is the name of the enzyme involved in Step 2 ___ citrate synthase ___ (6) Which step(s) serve as control points for the pathway illustrated__ 1, 2, 5 (or 5 + 6), 7 __ (7) At which step is there a nucleoside triphosphate produced and what is the 3-letter abbreviation for that compound _____ GTP _____ (8) Under the circumstances where there is an excess supply of acetyl-S-CoA available, the addition of oxaloacetate to twice the normal level will allow the cycle to operate at a speed which is a) unchanged d) many times normal b) twice normal
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This note was uploaded on 03/30/2010 for the course CH 369 taught by Professor Kbrowning during the Spring '07 term at University of Texas.

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CH369 exam3s04 - Written Answers 1 The compound 3-5 cyclic...

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