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Carbohydrate Metabolism

Carbohydrate Metabolism. Aulanni’am Biochemistry Laboratory Chemistry Departement Brawijaya University. Carbohydrates. Carbohydrates are the most abundant organic molecules in nature Photosynthesis energy stored in carbohydrates;

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Carbohydrate Metabolism

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  1. Carbohydrate Metabolism Aulanni’am Biochemistry Laboratory Chemistry Departement Brawijaya University Aulani "Biokimia" Presentation 3

  2. Aulani "Biokimia" Presentation 3

  3. Carbohydrates • Carbohydrates are the most abundant organic molecules in nature • Photosynthesis energy stored in carbohydrates; • Carbohydrates are the metabolic precursors of all other biomolecules; • Important component of cell structures; • Important function in cell-cell recognition; • Carbohydrate chemistry: • Contains at least one asymmetric carbon center; • Favorable cyclic structures; • Able to form polymers Aulani "Biokimia" Presentation 3

  4. Carbohydrate Nomenclature • Carbohydrate Classes: • Monosaccharides (CH2O)n • Simple sugars, can not be broken down further; • Oligosaccharides • Few simple sugars (2-6). • Polysaccharides • Polymers of monosaccharides Aulani "Biokimia" Presentation 3

  5. Carbohydrate Nomenclature • Monosaccharide (carbon numbers 3-7) • Aldoses • Contain aldehyde • Name: aldo-#-oses (e.g., aldohexoses) Memorize all aldoses in Figure ? • Ketoses • Contain ketones • Name: keto-#-oses (ketohexoses) Aulani "Biokimia" Presentation 3

  6. Monosaccharide Structures Conformation of monosaccharide Conformation of glucose Aulani "Biokimia" Presentation 3

  7. Disaccharides • Simplest oligosaccharides; • Contain two monosaccharides linked by a glycosidic bond; • The free anomeric carbon is called reducing end; • The linkage carbon on the first sugar is always C-1. So disaccharides can be named as sugar-(a,b)-1,#-sugar, where a or b depends on the anomeric structure of the first sugar. For example, Maltose is glucose-a-1,4-glucose. Aulani "Biokimia" Presentation 3

  8. Structures of Disaccharides Note the linkage and reducing ends Aulani "Biokimia" Presentation 3

  9. Polysacchrides • Also called glycans; • Starch and glycogen are storage molecules; • Chitin and cellulose are structural molecules; • Cell surface polysaccharides are recognition molecules. • Glucose is the monosaccharides of the following polysacchrides with different linkages and banches • a(1,4), starch (more branch) • a(1,4), glycogen (less branch) • a(1,6), dextran (chromatography resins) • b(1,4), cellulose (cell walls of all plants) • b(1,4), Chitin similar to cellulose, but C2-OH is replaced by –NHCOCH3 (found in exoskeletons of crustaceans, insects, spiders) Aulani "Biokimia" Presentation 3

  10. Overview of Glucose Catabolism • Cells catabolize organic molecules and make ATP two ways: • Substrate-Level Phosphorylation • Glycolysis • Krebs (TCA) Cycle • Oxidative Phosphorylation • Electron Transport Chain Aulani "Biokimia" Presentation 3

  11. Overview of Glucose Catabolism Aulani "Biokimia" Presentation 3

  12. Overview of Glucose Catabolism • Net reaction • Glycolysis • Biochemical pathway that produces ATP by substrate-level phosphorylation. • Yields a net of two ATP molecules for each molecule of glucose catabolized. • Every living creature is capable of carrying out glycolysis. • Most present-day organisms can extract considerably more energy from glucose through aerobic respiration. Aulani "Biokimia" Presentation 3

  13. Glucose priming Aulani "Biokimia" Presentation 3

  14. P P Cleavage and rearrangement Aulani "Biokimia" Presentation 3

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  17. Krebs Cycle • Cycle is also known as • Tricarboxylic acid (TCA) cycle • Citric acid cycle • After pyruvate has been oxidized, acetyl- CoA feeds into the Krebs cycle. • Krebs cycle is the next step of oxidative respiration and takes place in mitochondria. Occurs in three stages: • Acetyl-CoA binds a four-carbon molecule and produces a six-carbon molecule. • Two carbons are removed as CO2. • Four-carbon starting material is regenerated. citric acid Aulani "Biokimia" Presentation 3

  18. Aerobic Respiration • The pyruvic acid formed by glycolysis enters interior of mitochondria. • Converted by coenzyme A to 2 molecules of acetyl CoA and 2 C02. • Acetyl CoA serves as substrate for mitochondrial enzymes in the aerobic pathway. Aulani "Biokimia" Presentation 3

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  23. Krebs Cycle • Generates two ATP molecules per molecule of glucose. • Generates many energized electrons which can be directed to the electron transport chain to drive synthesis of more ATP: • 6 NADH per molecule of glucose • 2 FADH2 per molecule of glucose Aulani "Biokimia" Presentation 3

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  27. Glycolysis Aulani "Biokimia" Presentation 3

  28. KREBS CYCLE • Takes place in Mitochondrion when oxygen is present • Pyruvic acid from glycolysis is trimmed to a 2 carbon compound • Remaining carbon from glucose => CO2 • Hydrogens transferred • NAD+ => NADH • FAD => FADH • Products of kreb cycle • 3 NADHs • 1 FADH2 • 2 ATP Aulani "Biokimia" Presentation 3

  29. The Cori Cycle • The reconversion of lactic acid to pyruvate sees the removal of fatiguing lactate from the site of production. • This forms the theoretical basis for the cool-down. • As the glycolysis pathway is reversible lactic acid can eventually be anabolised into glucose and stored in the liver, muscles or blood. Aulani "Biokimia" Presentation 3

  30. Electron Transport System Aulani "Biokimia" Presentation 3

  31. Electron Transport System Aulani "Biokimia" Presentation 3

  32. Energy • Capacity to performwork. • Two examples: 1. Kinetic energy 2. Potential energy Aulani "Biokimia" Presentation 3

  33. SUN Kinetic Energy • Energy in the process of doing work. • Energy of motion. • Examples: 1. Heat 2. Light energy Aulani "Biokimia" Presentation 3

  34. GAS Potential Energy • Energy that matter occupies because of it’s location, arrangement, or position. • Energy of position. • Examples: 1. Water behind a dam 2. Chemical energy (gas) Aulani "Biokimia" Presentation 3

  35. adenine phosphate group P P P ribose Question: Answer: • What isATP? • adenosine triphosphate (ATP) • Components: 1. adenine: nitrogenous base 2. ribose: five carbon sugar 3. phosphate group: chain of three Aulani "Biokimia" Presentation 3

  36. Answer: • Works by the direct chemical transfer of a phosphate group. • This is called “phosphorylation”. • The exergonic hydrolysis of ATP is coupled with the endergonic processes by transferring a phosphate group to another molecule. Aulani "Biokimia" Presentation 3

  37. Adenosine triphosphate (ATP) P P P Hydrolysis (add water) + P P P Adenosine diphosphate (ADP) Hydrolysis of ATP • ATP + H2O  ADP + P (exergonic) Aulani "Biokimia" Presentation 3

  38. Adenosine triphosphate (ATP) P P P Dehydration synthesis (remove water) + P P P Adenosine diphosphate (ADP) Dehydration of ATP ADP + P  ATP + H2O (endergonic) Aulani "Biokimia" Presentation 3

  39. thank you to be continued Aulani "Biokimia" Presentation 3

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