BCHM 3050 1st Edition Lecture 31Outline of Last Lecture I. PolysaccharidesII. ATP (Adenosine triphosphate)III. Glycolysis: OverviewIV. Step 1V. Step 2VI. Step 3VII. Step 4VIII. Step 5IX. Step 6X. Step 7Outline of Current Lecture I. Step 8II. Step 9III. Step 10IV. Pyruvate KinaseV. Glucokinase vs. HexokinaseVI. Energy InvestmentVII. Energy PayofVIII. Regulation of GlycolysisIX. Metabolic Fate of PyruvateX. Lactic Acid FermentationXI. Alcohol Fermentation XII. Practice QuestionsCurrent LectureI. Step 8a. 3 converted to 2 position – (seems like a simple move from carbon 3 to carbon 2)but it involves an intermidiate (2, 3 bisphosphoglycerate)b. Phosphoglyceratemutase – belongs to the class of isomerasesII. Step 9a. Dehydration reaction – losing waterb. Do not want to consume too much fluoride because you can indirectly slow down glycolysisIII. Step 10These 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.a. Alanine is a by-product of the Krebs Cycleb. All are allosteric – act on a site diferent than the reaction sitec. Net gain of 2 ATP at the end of glycolysis, but per reaction you only get 1 ATP because the rest is given of by heatd. Delta G = net free energyIV. Pyruvate Kinasea. The modification is phosphorylationb. The levels of insulin and glucagon directs phosphorylation vs. dephosphorylationc. Direct covalent modification works on pyruvate kinaseV. Glucokinase vs. Hexokinasea. Glucokinase is the sister enzyme to hexokinaseb. Glycogen – alpha 1, 4 c. Glucokinase works in the liver and is a much higher pay in value d. Km of the two enzymes is vastly diferent – hexokinase is 10 times lower à means that it has a better affinitye. Hexokinase is the enzyme that usually carrier out glycolysisf. Too much glucose à use of glucokinaseg. Insulin is needed to activate glucokinaseVI. Energy Investmenta. Glucose is phosphorylated twice, and cleaved in half to form two triosesb. 2 ATP are consumedc. Hexose is cleaved into 2 triosesVII. Energy Payofa. DHAP is converted to Gald-3Pb. Two Gald-3P is oxidized to pyruvatec. 2 NADH and 4 ATP are producedd. NADH is generated with dehydrogenase – NAD+ is getting reduced to NADHe. Dehydrogenase also carried out phosphorylation so technically it is also a kinaseVIII. Regulation of Glycolysisa. 3 enzymes are regulated during glycolysisb. Too much glucose in the liver àglucokinase will take presidence and be activatedby insulinc. Glucokinase happens in the liver and doesn’t get inhibited by glucose-6-phosphated. Hexokinase happens in the other tissues and does get inhibited by glucose-6-phsophatee. Insulin promotes glycolysis (general rule) and breakdown in the bloodstreamf. Glucagon inhibits glycolysisg. Glucagon directly phosphorylates phosphoenolpyruvate (only one to get directly phosphorylated)IX. Metabolic Fate of Pyruvatea. By products are CO2 and waterb. Produce 2 NADHsc. 2 types of Anaerobic respiration – homolactic fermentation and alcoholic fermentationd. Homolactic fermentation – pyruvate converted to lactate; reversible (ex. Occurs with heavy exercise and is what causes the painful cramps)e. Alcoholic fermatation – irreversible; converts pyruvate to CO2 and ethanolf. Aerobic respiration – citric acid cycleX. Lactic Acid Fermentationa. Lactate dehydrogenase – suggests oxidation/reduction is occurringb. NADH gets recycled/oxidized to NAD+ à NAD+ goes to participate in glycolysis later onc. Pyruvate get reduced to lactated. Important to have lactic acid fermentation is the absence of oxygen in order to produce NAD+ to be used in glycolysisXI. Alcohol Fermentation a. Pyruvate loses CO2 to form acetaldehyde (3C atoms à 2C atom)b. Alcohol dehydrogenase recycles NADH and converts acetaldehyde to ethanol (aldehyde group in acetaldehyde is reduced to OH group in ethanolc. Too much NADH in the liver slows down metabolism XII. Practice Questionsa. A high concentration of Glucose 6-P is inhibitory to which enzyme?i. Hexokinaseb. What are 3 mechanisms for altering the flux through the glycolytic pathway?i. Allosteric control of enzyme activityii. Genetic regulation of enzyme concentrationiii. Covalent modification of the enzymec. Phosphofructokinase, the major flux-controlling enzyme of glycolysis is allosterically inhibited by ___ and activated by ___.i. ATP,
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