2009 Worksheet_ Thermodynamics of glycolysis

2009 Worksheet_ Thermodynamics of glycolysis - metabolites....

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Worksheet #6: Thermodynamics of Glycolysis Consider reaction A below: Glyceraldehyde 3-phosphate + P i + NAD + 1,3-Bisphosphoglycerate + NADH + H + ∆G’ 0 ≈ 5kJ/mole a) Draw the structures for Glyceraldehyde 3-phosphate (G3P) and 1,3-Bisphosphoglycerate (1,3-BPG). b) Is this an Oxidation, Reduction or both? Why? c) Which step of glycolysis is it? What is the name of the enzyme that catalyzes this reaction? d) Is this reaction endergonic or exergonic under standard conditions? Why or why not? e) In the cytosol we have the following concentrations: [G3P] = 3μM; [NAD + ] = 5mM; [NADH] = 1mM; [P i ] = 15mM. In order for this reaction to occur in the cell what would [1,3BPG] have to be? f) Is your result from (e) the minimum or maximum concentration needed for the glycolytic reaction? How much 1,3-BPG would you need for the reaction to be part of gluconeogenesis? g) What is gluconeogenesis? h) Write out the reaction B that follows reaction A in glycolysis. Draw the structures of the
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Unformatted text preview: metabolites. What is the name of the enzyme? Is it an oxidation, reduction, both? i) This reaction is much more favorable with G 0 -20 kJ/mole. What would Q have to be in order for this reaction to proceed in the forward direction? j) What is Q under the conditions in the cell, if [glycerate 3-phosphate] = 13.5 M; [ADP] = 1mM; [ATP] = 10mM and [1,3BPG] = from (e)? Will the reaction occur with the concentration of 1,3-BPG obtained in (e)? k) How many moles of ATP (for each mole of glucose) does this step in glycolysis produce? l) Steps 6 and 7 in glycoysis constitute an energy-coupling process. What is the common intermediate? Why is it coupled? m) What is the combined G ? Write the NET equation and the NET mass-action ratio (Q) for steps 6 and 7. n) What is NET G for the combined reaction? What is the advantage of that value?...
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This note was uploaded on 02/02/2010 for the course BIOCHEM Biochem440 taught by Professor Dr.klevit during the Winter '09 term at University of Washington.

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