Name NetID 30 2 pts What is the thermodynamically favorable direction of each of the following two reactions when the reactants are initially present in equimolar amounts ATP ADP Pi Creatine phosphate creatine Pi Glycerol 3 phosphate glycerol Pi Circle one arrow or G 30 5 kJ mol G 43 3 kJ mol G 9 2 kJ mol for each reaction Reaction 1 ATP creatine creatine phosphate ADP Reaction 2 ATP glycerol glycerol 3 phosphate ADP 31 4 pts The reactions catalyzed by hexokinase and phosphofructokinase have G s of 16 7 and 14 2 kJ mol respectively and because of these relatively high negative G s either enzyme could be used to regulate glycolysis eg by allosteric inhibition In most cells however one of these enzymes is not used to regulate glycolysis Which enzyme is not regulated and why is this enzyme not used as a control site 2 pts Hexokinase is not used to regulate glycolysis since the product of hexokinase glucose 6 phosphate is used by pathways other than glycolysis PPP and glycogen synthesis 2 pts Inhibition of hexokinase would also inhibit these other pathways in addition to glycolysis PFK is the first non reversible enzyme in glycolysis whose product is specific to glycolysis give extra credits if say that hexokinase is allosterically regulated in muscles by high G6P 1 Name NetID 32 7 pts In class I have made an analogy between the blood glucose regulation and the heating cooling system of a home Describe or draw a diagram showing how the body regulates high blood sugar levels after eating a chocolate bunny Include the name of the organs and hormones involved and their role in blood glucose regulation Make sure to also include how the rates of glycolysis and gluconeogenesis are affected 1 pt Liver furnace AC removes from or add glucose to blood accept any of these descriptions Pancreas thermostat glucostat blood glucose sensor accept any of these descriptions 1pt High blood sugar causes release of insulin from pancreas 1pt insulin stimulates liver to take up glucose 1 pt insulin turns off pathways to make glucose 1 pt Blood sugar levels go back to normal 1 pt glycolysis up 1 pt gluconeogenesis down 2 Name NetID 33 4 pts Fructose can be converted to pyruvate by glycolysis However the point of entry of fructose into the glycolytic pathway depends on tissue type Compare the point s of entry of fructose in adipose tissue to that of liver cells 2pts In the liver Fructose enters glycolysis by first being converted to GAP and DHAP 2 pts In adipose tissues fructose enters glycolysis by getting phosphorylated to F6P 34 2 pts List two molecules that can be converted to glucose other than the gluconeogenesis intermediates by the gluconeogenesis pathway Certain amino acids Alanine Lactate Glycerol 35 4 pts Give two reasons as to why the gluconeogenesis pathway could not simply be the same enzymatic reactions as glycolysis but in reverse 2 pts The G for the overall glycolysis pathway is very negative 96 kJ mol If gluconeogenesis was to use the same enzymes as glycolysis but in reverse it would have a large G value therefore it would be thermodynamically unfavorable 2pts Sharing of the exact same enzymes between two pathways but in reverse would prevent the reciprocal regulation of the pathways 3 Name NetID 36 6 pts The degradation of alanine yields pyruvate and the degradation of leucine yields acetyl CoA Can the degradation of these amino acids replenish the pool of citric acid cycle intermediates more specifically oxaloacetate Explain Circle one 1pt Alanine Yes No 2 pts Why Pyruvate can be converted directly to oxaloacetate which can be used to generate oxaloacetate by the enzyme pyruvate carboxylase 1 pt Leucine Yes No 2 pts Why No acetyl CoA cannot be converted to oxaloacetate in the TCA cycle At the beginning of the TCA cycle oxaloacetate is condensed with acetylCoaA generating citrate At the end of the cycle oxaloacetate is recycled NO new oxaloacetate is generated by the entry of acetyl Coa into the TCA cycle Could also get full credit if said Yes two molecules of acetylCoA could be used to make one new OAA via the the glycoxylate cycle but only in plants and prokaryotes 37 5 pts total Answer the following a 1 pt Using the table below determine whether the following reactions will proceed as written Indicate Yes or No Ethanol Blue acetaldehyde Orange 2 H YES or NO Circle one b 4 pts Calculate Go for the above reaction F 96 5 kJ V mol 4 Name NetID 2 pts for finding the redox value Since 0 2 0 05 0 15 V G nF Go 2 x 96 5 kJ V mol x 0 15 V 28 95 kJ mol 2 pts for finding the G value could still get the 2 pts for finding the G even if it was calculated using the wrong redox value as determined beforehand oxidant reductant n E o V acetaldehyde ethanol 2 0 20 Blue Orange 2 0 05 END OF EXAM 5
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