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Metabolism of carbohydrates

Metabolism of carbohydrates. 1. summarize. 2. Digestion & absorption. • Hydrolyzed by enzyme. • Final products - glucose. • active absorptive process at small intestine. 3.blood sugar. • the sources & outlet. Catabolism (H 2 0,CO 2 ,ATP). Dietary carbohydrate.

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Metabolism of carbohydrates

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  1. Metabolism of carbohydrates 1. summarize

  2. 2. Digestion & absorption • Hydrolyzed by enzyme • Final products - glucose • active absorptive process at small intestine

  3. 3.blood sugar • the sources & outlet

  4. Catabolism (H20,CO2,ATP) Dietary carbohydrate Liver ,muscle glycogen Liver glycogen Blood glucose Other substrates Glucogenesis (A.A,lactate,etc) glycosuria

  5. • blood sugar concentration is regulated by tissues,hormones Decreasing blood sugar level: hormone insulin

  6. elevating blood sugar level: hormone Glucagon,epinephrine,glucocorticoid, growth hormone

  7. Catabolism (H20,CO2,ATP) Dietary carbohydrate Liver ,muscle glycogen Liver glycogen Blood glucose Other substrates Glucogenesis (A.A,lactate,etc) glycosuria

  8. Hyperglycosemia: >7.2mmol/L Hypoglycosemia: <3.9mmol/L

  9. • The tolerance to carbohydrates Tolerance test for glucose

  10. 4. the catabolic pathway of carbohydrates

  11. catabolic pathway of carbohydrates Aerobic oxidation anaerobic glycolysis pentose pathway

  12. A. Anaerobic glycolysis • concept Glycolysis is the sequence of reactions that converts glucose into lactate with the concomitant production of ATP,under anaerobic conditions

  13. • the reaction site: cytosol • basic process (4 phases)

  14. 1) phosphorylation of hexoses G6P G

  15. F6P G6P

  16. FBP F6P

  17. • the characteristics of HK,PFK • the changes of the energy • the significance

  18. 己糖激酶（HK） a 二亚基的变构酶 b 催化不可逆反应，关键酶 ΔGo = -4.5 Kcal/mol c 葡萄糖激酶是肝中存在的己糖激酶的同工酶

  19. 高糖膳食后，肝中的 G G6P Gn 储存

  20. 磷酸果糖激酶（PFK） a 四亚基的变构酶 b 催化不可逆反应 关键酶 ΔGo = -3.4 Kcal/mol c 酵解过程中的主要限速酶 ★、 磷酸化酶 （phosphorylase） a 催化反应， α-1,4 糖苷键 磷酸解 b 产物 G1P Gn-1

  21. 2) Formation of glyceraldehyde-3- phosphate (G3P) by cleavage and isomerization DAP G3P DAP

  22. 3) Formation of pyruvate a. dehydrogenation BPG G3P

  23. b. energy released BPG 3PG

  24. c. transfer phosphoryl group 2PG 3PG

  25. d. dehydrate 2PG PEP

  26. e. energy released PEP

  27. 4) reduction of pyruvate to lactate

  28. • summarize a. concept b. the reaction site c. basic process (4 phases) d.key enzyme,limited enzyme e. the changes of energy

  29. Consumption & generation of ATP in glycolysis ATP change per glucose reaction - 1 G-----------G6P F6P--------FBP -1 (2) BPG----(2) 3PG +2 (2)PEP-------(2)pyruvate +2 net +2

  30. f. characteristics g. Physiologic role of glycolysis • the control of glycolysis a. enzymes b. hormones c. ATP/ADP

  31. LDH CH3 - C- COOH CH3-CH-COOH O OH + + NADH+H+ NAD+

  32. B. Aerobic oxidation of glucose • general

  33. lack of O2 O2 lactate pyruvate acetyl CoA Citric acid cycle Biological oxidation CO2,H2O, energy

  34. • the reaction site • basic process (3 phases)

  35. glycolysis • (G----------pyruvate) 2) formation of acetylCoA from pyruvate

  36. •Components of pyruvate dehydrogenase complex

  37. 3) Citric acid cycle a. acetyl CoA entering Citric acid cycle (synthesis of citric acid )

  38. b. dehydrogenation & decarboxylation

  39. • In this stage produced: 2 molecules of CO2 2 pairs of NADH+H+ 1 molecule of GTP

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