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Major Pathways. 1. Glycolysis2. Citric acid cycle3. Gluconeogenesis4. Glycogen metabolism (a) Glycogenesis (b) Glycogenolysis. 2. Saba Abdi. . . . I. Glycolysis (Embden Meyerhof Pathway): A. Definition: 1. Glycolysis means oxidation of glucose to give pyruvate (in the
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1. Carbohydrate Metabolism An Overview
General Biochemistry-II(BCH 302)
Dr . Saba Abdi
Asst . Prof. Dept. Of Biochemistry
College Of Science
King Saud University. Riyadh.KSA
2. Major Pathways 1. Glycolysis
2. Citric acid cycle
3. Gluconeogenesis
4. Glycogen metabolism
(a) Glycogenesis (b) Glycogenolysis 2 Saba Abdi
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15. Kreb Cycle 15 Saba Abdi
16. Electron Transport Chain 16 Saba Abdi
17. Summary 17 Saba Abdi
18. Total energy yield Glycolysis? 2 ATP
Krebs Cycle? 2 ATP
ETC ? 32 ATP
Total? 36 ATP
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19. Glycogen Metabolism 19 Saba Abdi
20. Glycogenesis: Glycogenesis is the formation of glycogen from glucose. Glycogen is synthesized depending on the demand for glucose and ATP (energy). If both are present in relatively high amounts, then the excess of insulin promotes the glucose conversion into glycogen for storage in liver and muscle cells.
In the synthesis of glycogen, one ATP is required per glucose incorporated into the polymeric branched structure of glycogen. actually, glucose-6-phosphate is the cross-roads compound. Glucose-6-phosphate is synthesized directly from glucose or as the end product of gluconeogenesis.
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21. Glycogenolysis
In glycogenolysis, glycogen stored in the liver and muscles, is converted first to glucose-1- phosphate and then into glucose-6-phosphate. Two hormones which control glycogenolysis are a peptide, glucagon from the pancreas and epinephrine from the adrenal glands.
Glucagon is released from the pancreas in response to low blood glucose and epinephrine is released in response to a threat or stress. Both hormones act upon enzymes to stimulate glycogen phosphorylase to begin glycogenolysis and inhibit glycogen synthetase (to stop glycogenesis).
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22. . Glycogen is a highly branched polymeric structure containing glucose as the basic monomer. First individual glucose molecules are hydrolyzed from the chain, followed by the addition of a phosphate group at C-1. In the next step the phosphate is moved to the C-6 position to give glucose 6-phosphate, a cross road compound.
Glucose-6-phosphate is the first step of the glycolysis pathway if glycogen is the carbohydrate source and further energy is needed. If energy is not immediately needed, the glucose-6-phosphate is converted to glucose for distribution in the blood to various cells such as brain cells.
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