NAME:______________________________ NETWORK ID:___________________ !1!!!!!!!!!!!!!!!MCB!450!–!Fall!2014!Exam!III!November!6th,!2014!Form!A!!Choose!the!BEST!answer!from!the!available!choices.!Only!nonHgraphing!calculators!are!permitted!for!use!on!this!exam.!!Section!1H!29!MultipleHchoice!Questions.!!Each!question!is!worth!4!points.!!!1.!!The!reactions!below!have!the!following!standard!free!energy!changes:!!!!!!!!!!1,3:bisphosphoglycerate!!3:phosphoglycerate!+!Pi! ∆G’°!=!:49.4!kJ/mol!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!ATP!!ADP!+!Pi! ! ! ∆G’°!=!:30.5!kJ/mol!!!!!!!!What!is!the!overall!∆G’°!for!the!following!reaction?!!! 1,3:bisphosphoglycerate!+!ADP!::>!3:phosphoglycerate!+!ATP!! ! !a. :18.9!kJ/mol!b. +18.9!kJ/mol!c. +40.0!kJ/mol!d. :79.9!kJ/mol!e. +79.9!kJ/mol!!!!!!!!NAME:______________________________ NETWORK ID:___________________ !2!2.!!The!ultimate!product!of!complete!oxidation!of!carbohydrates!is!________.!!a. O2!b. CO2!c. acetyl!CoA!!d. pyruvate!!e. acetate!ion!!!!3.!!A!reaction!that!best!serves!as!a!control!point!in!metabolic!pathways!________.!!a. is!a!near!equilibrium!reaction!!b. has!a!large!positive!△G!!c. is!metabolically!irreversible!!d. follows!Michaelis:Menten!kinetics!!e. is!endergonic!!4.!!ATP!is!thermodynamically!suited!as!a!carrier!of!phosphoryl!groups!in!animal!cells!because:!a. it!is!kinetically!stable!under!cell!conditions.!b. it!is!not!hydrolyzed!in!cells!without!enzyme!action.!c. it!is!intermediate!in!group:transfer!potential.!d. it!is!thermodynamically!unstable!under!cell!conditions.!e. All!of!the!above!choices!are!correct.!!!!5.!!!Which!of!the!following!reactions!is/are!thermodynamically!more!favorable!then!the!ATP!hydrolysis!reaction?!a.!!Phosphoenolpyruvate!(PEP)!to!pyruvate!b.!!2:Phosphoglycerate!to!phosphoenolpyruvate!(PEP)!!c.!!1,3:Bisphosphoglycerate!to!3:phosphoglycerate!d.!!Acetyl!CoA!to!acetate!and!CoA!e.!!Answer!choices!a!and!c!are!both!correct.!NAME:______________________________ NETWORK ID:___________________ !3!6.!!The!catabolism!of!1!mole!of!glucose!to!lactate!in!the!glycolytic!pathway!is!accompanied!by!the!reduction!of!how!many!moles!of!O2?!!a. 0!b. 2!c. 4!d. 6!e. 8!!7.!!The!conversion!of!1!mol!of!fructose!1,6!bisphosphate!to!2!mol!of!pyruvate!by!the!glycolytic!pathway!results!in!a!net!formation!of:!a. 1!mol!of!NAD+!and!2!mol!of!ATP!b. 1!mol!of!NADH!and!1!mol!of!ATP!c. 2!mol!of!NADH!and!2!mol!of!ATP!d. 2!mol!of!NADH!and!4!mol!of!ATP!e. 2!mol!of!NAD+!and!4!mol!of!ATP!! ! !!8.!!Which!of!the!following!is!NOT!an!intermediate!of!the!glycolytic!pathway?!a. 1,3:bisphosphoglycerate!b. Pyruvate!c. 2:phosphoglycerate!d. Fructose!1:phosphate!e. Phosphoenolpyruvate!!9.!!Which!is!NOT!among!the!possible!fates!of!pyruvate!after!glycolysis?!!a. Conversion!to!alanine.!b. Reduction!of!its!carbons!by!the!citric!acid!cycle.!!c. Conversion!to!ethanol.!d. Conversion!to!oxaloacetate.!!e. Conversion!to!lactate.!NAME:______________________________ NETWORK ID:___________________ !4!10.!!Glucokinase!has!a!Km!value!of!10.0!mM,!whereas!hexokinase!has!a!Km!value!of!0.1!mM.!!This!is!consistent!with!which!of!the!following?!a. Glucokinase!acts!on!glucose!at!low!glucose!concentrations.! !b. Glucokinase!acts!on!glucose!only!at!high!glucose!concentrations.! !c. Glucokinase!phosphorylates!most!of!the!glucose!at!low!glucose!levels.! !d. Hexokinase!acts!on!glucose!only!at!high!levels!of!glucose.! !e. Hexokinase!acts!at!about!half:maximal!velocity!at!glucose!concentrations!of!4:5!mM.!!!11.!!Hamsters!love!to!run!on!exercise!wheels.!!Prolonged!running!at!a!high!rate!of!speed!requires!ATP.!!Could!a!hamster!with!a!defective!gene!for!the!muscular!form!of!the!enzyme!lactate!dehydrogenase!meet!the!extra!ATP!demand!for!prolonged,!fast!wheel:running!by!maintaining!a!high!rate!of!glycolysis!when!muscles!are!operating!under!anaerobic!conditions?!Why!or!why!not?!a. No,!not!enough!NAD+!can!be!regenerated!for!glycolysis!to!continue!at!a!high!rate.!!b. No,!the!defective!gene!will!cause!accumulation!of!NAD+,!which!in!turn!will!inhibit!glycolysis.!!c. Yes,!the!defective!enzyme!has!no!effect!on!the!glycolytic!pathway.!!d. Yes,!the!enzyme!alcohol!dehydrogenase!will!supply!the!needed!NAD+!if!the!lactose!dehydrogenase!cannot.!!e. Yes,!the!extra!pyruvate!synthesized!by!the!muscles!can!be!converted!to!lactate!by!the!liver.!!!!12.!!!The!products!of!the!pathway!whose!first!enzyme!is!glucose:6:phosphate!dehydrogenase!are!CO2!and:!a. 2!NADH!+!1!pentose!phosphate!b. 2!NADH!+!1!hexose!phosphate!c. 2!NADP++!1!pentose!phosphate!d. 2!NADPH!+!1!hexose!phosphate!e. 2!NADPH!+!1!pentose!phosphate!!NAME:______________________________ NETWORK ID:___________________ !5!13.!!ATP!is!a!co:substrate!of!the!enzyme!phosphofructokinase!(PFK/PFK:1).!!In!most!species!ATP!is!also!an!inhibitor!of!PFK:1!at!higher!concentrations.!!Which!statement!below!would!provide!a!suitable!explanation!for!this!discrepancy?!!a. PFK:1!must!be!phosphorylated!by!ATP!in!the!active!site!and!the!phosphorylated!PFK:1!must!be!the!less!active!form.!!b. There!must!be!another!cofactor!interacting!with!ATP!at!high!concentrations!to!achieve!inhibition!of!PFK:1.!!c. ATP!actually!activates!the!reverse!of!the!reaction!preceding!the!PFK:1!step!in!the!pathway.!It!likely!has! no! direct!effect!on!PFK:1.!!d. There!are!two!sites!on!PFK:1!that!bind!ATP.!One!is!the!active!site;!the!other!is!the!regulatory!site!where!inhibition!occurs.!!e. ATP!is!unable!to!bind!to!the!allosteric!site!on!PFK!at!high!concentration.!!!!14.!!All!of!the!following!are!substrates!for!gluconeogenesis!EXCEPT:!a.!!Fatty!acids!b.!!Glycerol!c.!!Oxaloacetate!d.!!Lactic!acid!e.!!Alanine!!!15.!!Which!of!the!following!is!the!correct!statement!regarding!gluconeogenesis!?!a.!Fructose:2,6!bisphosphate!and!AMP!positively!regulate!gluconeogenesis.!b.!Citrate!and!ATP!negatively!regulate!gluconeogenesis.!c.!Fructose:2,6!bisphosphate!and!citrate!positively!regulat e!gluconeogenesis.!d.!Citrate!and!AMP!negatively!regulate!gluconeogenesis.!e.!Citrate!and!acetyl!CoA!positively!regulate!gluconeogenesis.!NAME:______________________________ NETWORK ID:___________________ !6!16.!!Which!of!the!following!reactions!is!NOT!part!of!the!pentose!phosphate!pathway?!a. C5!!+!!C5!!!!!C3!!+!C7!!!!by!the!enzyme!transketolase!b. C4!!+!!C5!!!!!C3!+!!C6!!by!the!enzyme!transketolase!c. C3!!+!!C7!!!!!C6!!+!!C4!!by!the!enzyme!transaldolase!d.
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