The conversion of lactate to glucose in the liver requires the input of 6 mol of ATP for every mol of glucose produced.Investigators can monitor the extent of this process in a rat liver preparation by administering [¹4C]lactate and measuring theamount of [¹4C]glucose produced.Because the stoichiometry of O, consumption and ATP production is known (about 5 ATP per O₂), investigators can predict theextra O₂ consumption above the normal rate after administering a given amount of lactate. However, when they actually measurethe extra O₂ used in the synthesis of glucose from lactate, it is always higher than what the stoichiometric relationships predict.What could explain this observation?Unproductive cycling of ADP and ATP occurs, with extra O, consumption.The initial production of lactate requires extra O₂.The conversion of [C]lactate to [C]glucose requires less ATP and less O₂.The production of [C]glucose uses more O, than the production of unlabeled glucose.

Glycolysis: a 6-carbon molecule of glucose-6-phosphate is broken down into 3-carbon pyruvate which…

Answered: The conversion of lactate to 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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Acetyl-CoA AG" = -7.7 kcal/mol COA Fatty acids Oxaloacetate Citrate AG" = -1.5 kcal/mol Isocitrate Krebs cycle is equilibrium at 25°C with coupled fatty acid biosynthesis. Calculate the free energy of the fatty acid biosynthesis (in kcal/mol), accounting for the concentrations of Oxaloacetate – 0.005 mM; Acetyl-CoA - 0.03 mM; Citrate - 0.001mM and Isocitrate – 0.06 mM.
The phosphorylation and oxidative decarboxylation of oxaloacetate by inorganic phosphate (Pi) to make phosphoenolpyruvate and carbon dioxide is endergonic under intracellular conditions. It is characterized by this equation: Oxaloacetate + Pi ←→ Phosphoenolpyruvate + H2O + CO2 ΔG’ = +24.6 kJ/mol The synthesis of GTP from GDP and inorganic phosphate (Pi) in solution is endergonic under intracellular conditions, and it is characterized by this equation: GDP + Pi ←→ GTP + H2O ΔG’ = +30.5 kJ/mol Write a new net thermodynamically coupled reaction equation that describes the synthesis of phosphoenolpyruvate from oxaloacetate using the hydrolysis of GTP to power the reaction and calculate the new net ΔG’ of this reaction. Show all of your work.
The enzyme pyruvate carboxylase is discovered in a bacterium that was thought not to contain it; in this case study, you’ll see how researchers study and characterize the enzyme, and, ultimately, show how it fits into a metabolic pathway. Following purification of the PYC enzyme by avidin-Sepharose affinity chromatography, the investigators carried out several experiments to characterize the enzyme. First, they ran samples of the enzyme on denaturing and non-denaturing gels; the results are shown in the figure to the right. In addition, they ran the protein through a calibrated gel filtration column, the results of which indicated that the PYC enzyme had a molecular weight of 540 kiloDaltons. In the figure, the rightmost column are where molecular weight standards of various sizes would occur if they’d been on the gels. Part A: There are four identical subunits in the PYC enzyme. And there are not four domains in the denaturing gel. Based on the image provided attached, how many chains…
Intramitochondrial ATP concentrations are about 5 mM, and phos- phate concentration is about 10 mM. If ADP is five times more abundant than AMP, calculate the molar concentrations of ADP and AMP at an energy charge of 0.85. Calculate AG for ATP hydrolysis at 37 °C under these conditions. The energy charge is the concentra- tion of ATP plus half the concentration of ADP divided by the total adenine nucleotide concentration: [ATP] + 1/2[ADP] [ATP] + [ADP] + [AMP]
Starting with glucose, there are five steps in the EMP/TCA metabolic pathways that produce NADH (which is converted to ATP or energy). Use class notes, Shuler, Kargi and DeLisa book, or the internet. 1. A. Draw the chemical structures of the reactant(s) and product(s); as well as a balanced chemical reaction for the step in the TCA (Krebs) cycle where isocitrate is converted to a-ketoglutarate (step 3 in the class notes). (You don't need to draw the structures of coenzyme A (COA), NAD* or NADH.) B. What enzymes catalyze steps 3 and 5 in the Kreb's cycle from the class notes? C. Would you categorize step 8 in the TCA cycle where malate is converted to oxaloacetate as an oxidation or reduction of malate? D. Considering that some energy is spent transporting acetyl-CoA to mitochondria, how much net energy (in kcal) is produced by converting 15 mol of glucose to CO₂ in the glycolysis & Krebs cycle pathways? E. How many kcals of energy from oxidizing 15 mol of glucose to CO₂ (your answer to…
The main location of ethanol metabolism in the body is the liver and the main route of detoxification includes liver alcohol dehydrogenases (ADH) located in the cytosol and aldehyde dehydrogenases (ALDH) located in the mitochondrion. Together these sequentially convert ethanol into acetate. A second (more minor) route of detoxification includes the microsomal ethanol oxidizing system (MEOS). 1. Based on the chemical structure, predict how permeable a biological membrane will be to ethanol (in the absence of a transporter/channel)?
The following question focuses on how the parameters regulating enzyme function might change, and how these might appear graphically on a Michaelis-Menten plot and a Lineweaver-Burke plot. Carbonic anhydrase is an enzyme that will convert CO2 and water into HCO3. CO2 + H20 > H+ + HCO3 There are many different isoforms of this enzyme. (see for instance http://en.wikipedia.org/wiki/Carbonic_anhydrase . Assume that one variant has a Km of 10 µM and a different variant has a Km of 100 µM. Draw on the same graph a typical Michaelis-Menton plot showing the alteration in the rate of carbonic anhydrase as the CO2 level is varied for the two different variants of enzyme, assuming the concentration of the enzyme (10 mM) in the test tube is kept constant. Assume that you have equal amounts of the two different variants of carbonic anhydrase in a number of test tubes and that the Vmax for both enzymes are the same. Be sure to label the axes. For the same conditions as above, draw a…
The Beutler test is used to diagnose GALT (UDP-glucose uridyltransferase) deficiency in infants. Blood from the heel is spotted onto filter paper and the spot is then subjected to an enzyme assay. Galactose 1-phosphate, NADP+ and UDP-glucose are added as substrates to the dried blood. The increase in absorbance at 340nm is measured over time which corresponds to reduction of NADP+ to NADPH . The amount of GALT activity in the blood of patients is therefore measured by stoichiometric relationship to the amount of NADPH produced from NADP+. However, GALT does not directly reduce NADP+ as you can see in the above diagram. Instead, the glucose 1-phosphate product from this reaction is shuttled into the oxidative phase of the pentose phosphate pathway by enzymes also present in RBCs. Which three (or possibly more if you must) enzymes downstream of GALT allow for quantitative correlation of a product of GALT with the appearance of NADPH? What is the stoichiometric relationship…
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…
How many net ATP are produced from the complete oxidation of one molecule of 1,3-bisphosphoglycerate (1,3 BPG) in a neuron?
During glycolysis, glucose is converted into fructose-6- phosphate in two successive reactions: glucose + ATP glucose 6-phosphate + ADP glucose 6-phosphate fructose 6-phosphate The AG' for the overall reaction is: +15.0 kJ/mol. -18.4 kJ/mol. -16.7 kJ/mol. → -15.0 kJ/mol. +18.4 kJ/mol. AG¹⁰ = -16.7 kJ/mol AG¹⁰ = +1.7 kJ/mol
Refer to the figure shown here, and determine the value of E for the overall oxidation/reduction reaction (refer to the book/lecture slides if you need help with the overall reaction). 121/202 + 2H+ + 2e → H₂0 NAD + H* + 2e → NADH O-1.136 volts O 0.496 volts O+1.136 volts voltsm -0.496 volts EU (volts) +0.816 - 0.320

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