BIOC 2300 Lecture 21: Lecture 21

• School: Dalhousie University
• Department: Biochem & Molecular Biology
• Course: BIOC 2300
• Professor: David Byers

Document Summary

Unique steps of gluconeogenesis regulation of phosphofructokinase interpreting and describing a diagram. Gluconeogenesis: humans use about 160 g of glucose per day. Reactions spontaneously occur towards equilibrium concentrations and lower free energy. Thermodynamically possible: negative dg, keq > 1, more products than substrates in equilibrium, exergonic reaction towards products, favorable reaction towards products. Possible only when linked to an exergonic reaction. Different enzymes and different side products make the reaction possible. Steps 1, 3 and 10 of glycolysis have a large negative dg: regulatory steps, irreversible, different enzymes catalyze different combined reverse reactions for gluconeogenesis. Diagram shows the dg for the full reactions (i. e. coupled to atp hydrolysis, nad+ reduction). The half reactions for the intermediates alone would look different. Therefore, gluconeogenesis is not an exact reversal of glycolysis. Three steps are catalyzed by non-glycolytic enzymes and generate different side products. H2o and h+ are omitted from the equations.