Glycolysis - Glycolysis: Derived from Greek words; Glykys =...

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Glycolysis: Derived from Greek words ; Glykys = Sweet, Lysis = splitting During this process one molecule of glucose (6 carbon molecule) is degraded into two molecules of pyruvate (three carbon molecule). Free energy released in this process is stored as 2 molecules of ATP, and 2 molecules of NADH. Glucose + 2NAD+ = 2Pyruvate + 2NADH + 2H+ δ G = -146 kJ/mol
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Fate of glucose in living systems Glucose + 6O 2 = 6CO 2 + 6H 2 O δ G o = -2840 kJ/mol Glucose + 2NAD + = 2Pyruvate + 2NADH + 2H + δ Go = -146 kJ/mol 5.2% of total free energy that can be released by glucose is released in glycolysis.
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Louis Pasteur (1822-1895)
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Historical Perspective Glycolysis was the very first biochemistry or oldest biochemistry studied. It is the first metabolic pathway discovered. Louis Pasture 1854-1864: Fermentation is caused by microorganism. Pastuer’s effect: Aerobic growth requires less glucose than anaerobic condition. Buchner; 1897: Reactions of glycolysis can be carried out in cell-free yeast extract. Harden and Young 1905: 1: inorganic phosphate is required for fermentation. 2: yeast extract could be separated in small molecular weight essential coenzymes or what they called Co-zymase and bigger molecules called enzymes or zymase. Inhibitor studies: Iodoacetate treatment resulted in the accumulation of fructose 1,6biphosphate. Similarly fluoride caused accumulation of 2- phosphoglycerate and 3-phosphoglycerate. 1940: with the efforts of many workers, complete pathways for glycolysis was established.
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There are 10 enzyme-catalyzed reactions in glycolysis. There are two stages Stage 1 : Reactions 1-5) A preparatory stage in which glucose is phosphorylated, converted to fructose which is again forphorylated and cleaved into two molecules of glyceraldehyde-3-phosphate. In this phase there is an investment of two molecules of ATP. Stage 2 : (reactions 6-10) The two molecules of glyceraldehyde-3- phosphate are converted to pyruvate with concomitant generation of four ATP molecules and two molecules of NADH. Thus there is a net gain of two ATP molecules per molecule of Glucose in glycolysis. Importance of phosphorylated intermediates: 1. Possession of negative charge which inhibit their diffusion through membrane. 1. Conservation of free energy in high energy phosphate bond. 1. Facilitation of catalysis.
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1. Hexokinase reaction: phosphorylation of hexoses (mainly glucose) I. This enzyme is present in most cells. In liver Glucokinase is the main hexokinase which prefers glucose as substrate. I.
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This note was uploaded on 02/09/2011 for the course BIOS 20182 taught by Professor Lahn during the Spring '11 term at UChicago.

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Glycolysis - Glycolysis: Derived from Greek words; Glykys =...

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