During the metabolism of glucose in anaerobic cells, the enzyme lactatedehydrogenase is essential to allow glycolysis to continue. This enzyme catalyzes thereduction of pyruvate to lactate. Why is this so essential?OA) It lowers the pH.B) It re-oxidizes NADH to NAD+.C) Lactate stimulates hexokinase activity.D) Pyruvate inhibits pyruvate kinase.

Lactate dehydrogenase catalyzes the interconversion of pyruvate and lactate. The enzyme is an…

Answered: During the metabolism of glucose in…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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Similar questions

Which reactions of glycolysis can be reversed? Which are irreversible? What is the significance of the metabolically irreversible reactions?
Organisms growing anaerobically cannot perform glycolysis for long without reducing the pyruvate from glycolysis into another compound, most commonly to lactate or to ethanol plus CO2. Both of these reactions are given below in their unbalanced forms. Explain in one sentence why one of these reducing steps is needed to sustain anaerobic glycolysis.
a) What happens during the two phases of glycolysis? Write the reaction steps of glycolysis showing their the enzymes that catalyze the reactions. (Draw only the structure of the first and last product) b) How many net moles of ATP can be synthesized from each mol of glucose? c) The overall equation for glycolysis?
Describe how a) Mean Arterial Pressure, b) Maximal Oxygen Consumption, and c) Blood Flow are determined using its formula. In addition, you should explain what those factors are including cardiac output, stroke volume, heart rate, resistance, a-vO2 difference, etc. Describe how many ATPs can be generated by complete cycles of beta oxidation of free fatty acid with 20 carbons. You should indicate how many cycles of beta oxidation and Krebs cycle, and total number of products as well
Concerning the use of pyruvate when ratio of NADH/NAD+ is low, what is the fate of the carbon labeled in pyruvate when metabolized under these conditions? a) Production of glucose b) Oxidation to CO2 via the TCA cycle c) Conversion to pyruvate to generate oxaloacetate to move electrons to the cytosol via the malate shuttle d) Pyruvate is never metabolized by the cell, instead pyruvate is converted to lactate and solely exported for the Cori cycle and dependent on the liver to recycle the carbon skeleton
Malate dehydrogenase is an enzyme that converts malate to oxaloacetate in the last stage of the TCA Cycle (citric acid cycle/Krebs cyde), represented by the following equation: NAD+ Malate Oxaloacetate NADH A group of students carried out an experiment to determine the optimum temperature for the activity of a commercially produced malate dehydrogenase (from yeast) at several different temperatures. A series of test tubes was set up containing 2.0 cm of phosphate buffer with a pH of 7.5, 0.1 cm? of NADH, 0.1 cm of malate dehydrogenase and 0.7 cm3 of water. The tubes were incubated in water baths at the various temperatures for 5 minutes. At certain time intervals each tube was placed in a colorimeter, set at an absorbance value of 1.0. The reaction was then started by adding 0.1 cm? of oxaloacetic acid to the tube. Enzyme activity was measured by following the decrease in absorbance for 120 seconds. The experiment was repeated to give duplicate results. Enzyme activity was then…
The pyruvate dehydrogenase complex catalyzes the synthesis of acetyl-CoA, a very important molecule in cellular metabolism. The reaction catalyzed by the pyruvate dehydrogenase enzyme complex is shown below. This reaction is tightly regulated, because it is essentially irreversible. Which of the following conditions is most likely to lead to the inhibition of pyruvate dehydrogenase in cells? (select two answers) High concentrations of acetyl-CoA High concentrations of pyruvate High concentrations of NADH High concentrations of NAD+ High concentrations of CoA
Although both hexokinase and phosphofructokinase catalyze irreversible steps in glycolysis and the hexokinase-catalyzed step is first, phosphofructokinase is nonetheless the pacemaker of glycolysis. What does this information tell you about the fate of the glucose 6-phosphate formed by hexokinase? Glucose 6-phosphate must be unstable and release its phosphoryl group over time. Glucose 6-phosphate must be utilized by other metabolic pathways. Glucose 6-phosphate must allosterically inhibit phosphofructokinase, but not hexokinase. Glucose 6-phosphate must be wasted when it is produced in excess.
Which of the listed glycolytic enzymes adds a phosphate group to ADP to produce ATP? 1.) pyruvate kinase 2.) hexokinase 3.) phosphofructokinase-1 4.) pyruvate dehydrogenase 5.) phosphexose isomerase 6.) lactate dehydrogenase
*Determine the ATP yield from the metabolism of one molecule of glucose under the following conditions: a) b) c) in a mammalian muscle cell carrying out anaerobic glycolysis. in Escherichia coli, an aerobic prokaryote in a mammalian brown fat cell, in which electron transport occurs without producing ATP
a) Using full chemical structures of substrates and products, draw the two possible pyruvate reduction pathways that regenerate NAD+ from NADH in the absence of oxygen gas. Give names of all compounds and enzymes involved. b) Draw the step in glycolysis that requires at least one of the above pathways to be functional in the absence of oxygen. Give names of all compounds and enzymes involved.
c) Some scientists debate whether it is correct to consider pyruvate as “the end of glycolysis”. Elaborate on this statement, discussing supporting and limiting facts.

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