Concept explainers
Interpretation: To determine the source of the “cargo” for
Concept introduction: In the glycolysis metabolic pathway, a glucose molecule breaks down into two pyruvate molecules. ATP and NADH are produced along with pyruvate. The net overall equation for the glycolysis process is as follows:
Electron transfer chain is defined as a series of biochemical reactions in which the electrons and hydrogen ions
Nicotinamide adenine dinucleotide is associated with the redox reactions in metabolism. Its reduced form is NADH and oxidized form is
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- What are the equilibrium concentrations of fructose 1,6-bisphosphate, dihydroxyacetone phosphate, and glyceraldehyde 3-phosphate when 1 mM fructose 1,6-bisphosphate is incubated with aldolase under standard conditions?arrow_forwardPhosphoglycerate mutase (PGM) catalyzes the interconversion of 3-phosphoglycerate (3PG) and 2-phosphoglycerate (2PG) in the glycolytic and gluconeogenic pathways. a) To what enzyme class does PGM belong? b) There are two distinct classes of PGM, one which is dependent on 2,3-bisphosphoglycerate (2,3-BPG), dPGM, and one which is not, iPGM. dPGM uses acid base chemistry and a phosphorylated histidine residue to interconvert 3PG and 2PG. The dPGM reaction proceeds with formation of 2,3-BPG as an intermediate. Propose a mechanism for the dPGM-catalyzed conversion of 3PG to 2PG that is consistent with this information. c) What is the purpose of 2,3-BPG (i.e., why does dPGM require it)?arrow_forwardThe glucose/glucose-6-phosphate substrate cycle involves distinct reactions of glycolysis and gluconeogenesis that interconvert these two metabolites. Assume that under physiological conditions, [ATP] = [ADP]; [P;] = 1 mM. Consider the glycolytic reaction catalyzed by hexokinase: ATP + glucose ADP + glucose-6-phosphate AG = - 16.7 kJ/mol (a) Calculate the equilibrium constant (K) for this reaction at 298°K, and from that, calculate the maximum [glucose-6-phosphate]/ Iglucose] ratio that would exist under conditions where the reaction is still thermodynamically favorable. (b) Reversal of this interconversion in gluconeogenesis is catalyzed by glucose-6-phosphatase: glucose-6-phosphate + H20 = glucose + P AG" = -13.8 kJ/molarrow_forward
- glycerol 3-phosphate forms the backbone of glycerosphospholipids. what 3-carbon intermediate in the glycolysis pathway is the immediate precursor of glycerol 3-phosphate?arrow_forwardWhat are four possible metabolic fates of glucose-6- phosphate?arrow_forwardIs GAPDH only a glycolytic enzyme? What are the other physiological functions of GAPDH?arrow_forward
- The glucose/glucose-6-phosphate substrate cycle involves distinct reactions of glycolysis and gluconcogenesis that interconvert these two metabolites. Assume that under physiological conditions, [ATP] = [ADP] and [Pi] =1 mM. Consider the following glycolytic reaction catalyzed by hexokinase: ATP + glucose = AG' = -16.7 kJ/mol ADP + glucose-6-phosphate (a) Calculate the equilibrium constant (K) for this reaction at 298 K, and from that, calculate the maximum [glucose-6-phosphate]/[glucose] ratio that would exist under conditions where the reaction is still thermody- namically favorable. (b) The reverse of this interconversion in gluconeogenesis is catalyzed by glucose-6-phosphatase: glucose-6-phosphate + H,0 = glucose + P, AGr = -13.8 kJ/mol K= 262 for this reaction. Calculate the maximum ratio of [glucose]/ [glucose-6-phosphate] that would exist under conditions where the reaction is still thermodynamically favorable. (c) Under what cellular conditions would both directions in the…arrow_forwardIntracellular concentrations in resting muscle are as follows: fructose- 6-phosphate, 1.0 mM; fructose-1,6-bisphosphate, 10 mM; AMP, 0.1 mM; ADP, 0.5 mM; ATP, 5 mM; and P, 10 mM. Is the phosphofructokinase reac- tion in muscle more or less exergonic than under standard conditions? By how much?arrow_forwardWith respect to glycogen, what is the likely fate of excess glucose 6-phosphate in muscle?arrow_forward
- In which of the following metabolic conversions is ATP “generated” during glycolysis? Glucose —> Glucose-6-phosphate 1,3-Bisphosphoglycerate —> 3-Phosphoglycerate Fructose-1,6-bisphosphate —> Dihydroxyacetone phosphate + Glyceraldehyde-3-phosphate Glucose-6-phosphate —> Fructose-6-phosphate 2-Phosphoglycerate —> 3-Phosphoglyceratearrow_forwardThe overall reactions for gluconeogenesis and glycolysis are given below. What is the energy cost (in ATP equivalents) of transforming one molecule of glucose to pyruvate (via glycolysis) and back to glucose (via gluconeogenesis)? Gluconeogenesis: 2 pyruvate + 4 ATP + 2 GTP + 2NADH + 4H₂O Glycolysis: Glucose + 2ADP + 2P₁ + 2NAD+ - 2 pyruvate + 2ATP + 2NADH + 2H+ + 2H₂000 Select one: O a. 2 ATP O b. 4 ATP O c. 6 ATP O d. 8 ATP Prev Page glucose + 4ADP + 2GDP + 2P₁ + 2NAD+ + 2H+ MI 21 22 00:508D DAD 1=1 SE 30: DONDOK 23 24 25 26 27 28 29 30 Report question issue B Next Page Garrow_forwardIntracellular concentrations in resting muscle are as follows: fructose6-phosphate, 1.0 mM; fructose-1,6-bisphosphate, 10 mM; AMP, 0.1 mM;ADP, 0.5 mM; ATP, 5 mM; and Pi, 10 mM. Is the phosphofructokinasereaction in muscle more or less exergonic than under standard conditions?By how much?arrow_forward
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