T2.2_Glycolysis - Glycolysis LEARNINGOBJECTIVES:

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Glycolysis LEARNING OBJECTIVES:  Know the different enzymes of glycolysis and  understand that it comprises of three stages – all  occurring in the cytosolic compartment.  Know that pyruvate is an important junction  point in glucose metabolism – being the  dominant product under aerobic conditions and  converting readily to lactate under anaerobic  conditions. The energy yield (as ATP) is  markedly different under the two processes.
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Learning objectives, contd. Explain how in aerobic glycolysis electrons are  transferred from the cytoplasm into mitochondria.  Understand the regulation of glycolysis, especially  as it relates to phosphofructokinase I and pyruvate  kinase. Appreciate the link between glyceraldehyde-3- phosphate dehydrogenase and lactate  dehydrogenase.
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Glucose metabolism under aerobic  and anaerobic conditions
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An outline of the glycolytic scheme The three steps of stage  I begin with the  phosphorylation of  glucose with  hexokinase.
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First reaction of glycolysis - Phosphorylation  catalyzed by hexokinase or glucokinase Phosphorylation of glucose achieves two objectives: (a) glucose-6-phosphate  cannot diffuse through the membrane and (b) addition of phosphate begins to  destabilize glucose thus facilitating its further metabolism.
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Glycolytic scheme – Stage I After phosphorylation, the next  step of glycolysis is  isomerization. This converts G- 6-P to F-6-P which is followed  by another phosphorylation,  mediated by phosphofructo- kinase I (PFK I). PFK I is an  allosteric enzyme that sets the  pace for glycolysis. It must be  remembered that two moles of  ATP have been used in  converting glucose to F-6-P.
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Glycolytic scheme – Stage II The 2 nd  stage of glycolysis begins with the splitting of F 1,6 bisphosphate by  aldolase yielding glyceraldehyde-3-phosphate and dihydroxyacetone  phosphate. These two compounds are isomers, readily interconverted by  triose phosphate isomerase .
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Glycolytic scheme – Stage III In stage III, glyceraldehyde 3- phosphate dehydrogenase mediates  the synthesis of 1,3 bisphospho- glycerate, an acyl phosphate (with a  high phosphoryl transfer potential)  provides the basis for harvesting  energy invested earlier during the  synthesis of F 1,6 bisphosphate from  glucose. Thus, the next step catalyzed  by phosphoglycerate kinase results in  the synthesis of ATP with the 
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This document was uploaded on 11/04/2011 for the course BMB 401 at University of Miami.

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T2.2_Glycolysis - Glycolysis LEARNINGOBJECTIVES:

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