CHEM 360 1st Edition Lecture 15 Outline of Last Lecture I Metabolism II ATP as the universal currency of free energy III Coupled Reactions IV Activated carriers V Regulation of metabolic processes Outline of Current Lecture I Glycolysis a First phase Reactions 1 5 no ATP generated b Second Phase Reactions 6 10 generation of ATP II Feeder pathway to glycolysis other sugars can also enter the glycolytic pathway III Regulation of glycolysis IV Glucose transporters V Fate of pyruvate under anaerobic conditions a In yeast Alcohol fermentation b In other microorganisms and exercising muscle Lactic acid fermentation VI Hypoxia Inducible Factor Current Lecture Regulation of Glucose Metabolism Insulin increases glycolysis Regulation of Metabolic Pathways Phosphorylation of an enzyme normally turns off the activity of the enzyme o But it is a reversible process so when the phosphoryl group is removed the enzyme will become active again Steady State Flow of Metabolic Pathways flux Can think of metabolic pathways like the lined up champagne glasses the rate of this action depends on the first glass Reciprocal Pathways Glycolysis and gluconeogenesis are examples of reciprocal pathways If turn off enzyme that converts E D then B will convert more to C and F will increase o And the opposite effect will increase A The energy status of the cell is often an important regulator of enzyme activity ATP AMP high energy charge AMP ATP low energy charge These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Due to the fact that there are two high energy bonds in ATP Energy charge regulates metabolism Energy charge is normally constant at 0 9 which can be seen on the graph Metabolic pathways are compartmentalized within cells Glycolysis is used both in eukaryotes and prokaryotes There are ten steps in glycolysis Use 2 ATP initially During second phase is where 4 molecules of ATP is generated along with 2 NADH 1st Stage of Glycolysis Phosphorylation of glucose and second phosphorylation of fructose 6P are the regulated steps and are irreversible Glycolysis Reaction 1 Phosphorylation Where first ATP comes in and is used Hexokinase When a substrate binds to hexokinase it changes its conformation Glycolysis Reaction 2 Isomerization by phosphoglucose isomerase All of these steps are fully reversible Glycolysis Reaction 3 Second Phosphorylation This is the committed step of glycolysis The enzyme of the committed step is Phosphofructokinase determines the rate of glycolysis and this step is irreversible Glycolysis Reaction 6 GAP is oxidized to 1 3 BPG 1 4 BPG means high phosphoryl group transfer potential o Precursor to 2 3 BPG in RBC Coupling of the two processes by one enzyme allows the conservation of energy released by oxidation Left graph uncoupled processes o Left also involves an acid Right graph coupled processes The free energies of the reactions of glycolysis under actual intracellular conditions in erythrocytes Means that these three steps are irreversible due to their very negative delta Gs Fructose enters the glycolytic pathway in the liver through the fructose 1 phosphate pathway Don t have to remember any of the enzymes Fructose can be converted to F 6P by hexokinase Hexokinase is only present in adipose tissue Regulation of glycolysis PFK PFK 1 The pacemaker of glycolysis the committed step Regulation of Allosteric Enzymes by Feedback Mechanism Intermediates upstream of A to the left o Will activate the committed step or the enzyme that you are talking about Intermediates downstream of A to the right o Will inhibit the committed step or the enzyme that you are talking about Regulation of Phosphofructokinase There is a muscle version of the enzyme and a liver version of the enzyme