Concept explainers
To analyze: The allosteric regulation of the enzyme phosphofructokinase by ATP and related molecules during glycolysis and to find whether the ATP that is considered to be allosteric regulator inhibits or stimulates the activity of the enzyme phosphofructokinase.
Concept introduction:
The enzyme phosphofructokinase plays its role in the most important regulatory step (energy investment step) of glycolysis. It converts fructose-6 phosphate to fructose-1,6 bisphosphate. The regulation of phosphofructokinase is said to be allosteric due to the binding of an effector molecule other than the enzyme's active site. Adenosine triphosphate (ATP) is known as the allosteric regulator for this enzyme in this step of glycolysis.
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Campbell Biology (10th Edition)
- Figure 27.3 illustrates the response of R (ATP-regenerating) and U (ATP-utilizing) enzymes to energy charge. a. Would hexokinase be an R enzyme or a U enzyme? Would glutamine: PRPP amidotransferase, the second enzyme in purine biosynthesis, be an R enzyme or a U enzyme? b. If energy charge = 0.5: Is the activity of hexokinase high or low? Is ribose-5-P pyrophosphokinase activity high or low? c. If energy charge = 0.95: Is the activity of hexokinase high or low? Is ribose-5-P pyrophosphokinase activity high or low?arrow_forward. In another key reaction in glycolysis, dihydroxyacetone phosphate (DHAP) is isomerized into glyceraldehyde-3-phosphate (GAP) Because ∆G°′ is positive, the equilibrium lies to the left. (a) Calculate the equilibrium constant and the equilibrium fraction of GAP from the above, at 37 °C. (b) In the cell, depletion of GAP makes the reaction proceed. What will ∆G be if the concentration of GAP is always kept at 1/100 of the concentration of DHAP?arrow_forwardWrite a balanced chemical equation for the pentose phosphate pathway in the first two modes depicted as shown, where (a) ribose-5-phosphate synthesis is maximized and (b) NADPH production is maximized, by conversion of the sugar phosphate products to glucose-6-phosphate for repeated operations of the pathway.arrow_forward
- Give typed full explanation Diagram the path of electron flow from NADH to the final electron acceptor during oxidative phosphorylation in mitochondria. For each electron carrier, indicate whether only electrons or both electrons and protons, are accepted/donated by that carrier. B) What would happen to this electron flow and what are the resulting consequences if myxothiazol is added to actively respiring mitochondria using succinate as an electron donor? C) Would you predict ubiquinone reduction to ubiquinol would be more favored at acidic pH or alkaline pH? Why? And as a result, would you predict Complex I active site for this reaction is closer to the N side or P side of the mitochondria?arrow_forwardPredict the effect of each of the following mutations on the pace of glycolysis in liver cells: (a) Loss of the allosteric site for ATP in phosphofructokinase (b) Loss of the binding site for citrate in phosphofructokinase (c) Loss of the phosphatase domain of the bifunctional enzyme that controls the level of fructose 2,6-bisphosphate (d) Loss of the binding site for fructose 1,6-bisphosphate in pyruvate kinasearrow_forwardKk155.arrow_forward
- Some of the biochemical reactions of GLYCOLYSIS are known to have a positive deltaG0, e.g. the cleavage of a 6 carbon compound into two, three-carbon molecules. ONE reason these types of reactions proceed in the forward direction in cells is that... A. hydrogen ions are allowed to flow down their concentration gradient to power the reaction. B. ... NADH is oxidized to NAD+ to power the reaction. C. ... products of the reactions are kept at low concentrations due to their rapid use in downstream reactions with negaive deltaG’s. D. ... ADP is phosphorylated to ATP to power the reaction.arrow_forwardHiarrow_forward2B. Calculate the total number of ATP that will be generated from the complete B-oxidation of oncobic acid (CH:(CH,),CH=CH(CH,),COOH; 15:1 cis-A9) in an organism that has all the standard required enzymes for metabolism but which pumps only 2 H" in complex I, 0 H' in complex II, 2 H* in complex III and 4 H' in complex IV. The F,F, ATPase is composed of 3 a/ß subunits and 10 c subunits. Show all of your calculations. HOarrow_forward
- complex 4 cytochrome C oxidase COxidation of one molecule of NADH by the ETC result in transport of 10 protons across the membrane. The c-ring of the ATP synthase in your experimental system contains 12 c subunits. Based on the "binding-change" mechanism of ATP synthesis, how many ATP molecules would be produced from one NADH molecule? n Name the processes that generate NADH during aerobic respiration. For each process, indicate thearrow_forwardDraw out the mechanismarrow_forwardGlycolysis is a degradative pathway of glucose.(a). Name the three (3) reactions that occur spontaneously in glycolysis(b). Phosphofructokinase (PFK) is the primary regulatory point of glycolysis andis regulated by substrate cycling. Explain substrate cycling with regard toPFK.(c). What is kinase enzyme reactions and name the four (4) kinase enzymereactions in the glycolysis.arrow_forward
- BiochemistryBiochemistryISBN:9781305577206Author:Reginald H. Garrett, Charles M. GrishamPublisher:Cengage Learning