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CARBOHYDRATES’ METABOLISM

Brief Introduction of Metabolism of Carbohydrates

yusufgadam
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CARBOHYDRATES’ METABOLISM

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  1. CARBOHYDRATES’ CARBOHYDRATES’ METABOLISM METABOLISM S S U M M A R I Z E D U M M A R I Z E D b b y y فسوي ىلع

  2. Presenting Presenting Note on; Note on; Metabolism  Metabolism of Carbohydrate  Major Pathways of Carbohydrate  Metabolism Digestion of Carbohydrates  Entry of Glucose into the Cells  Factors Determining Blood Glucose  level

  3. M Metabolism etabolism - From the Greek word; metabole – means “change” Is the general term that describes the different changes taking place in the body. The word (metabolism) refers to the sum of all chemical reactions that occur in living organism, including digestion and the transport of substance into/between different cells, in which case the set of reactions within the cells is called intermediary or intermediate metabolism(1).

  4. M Metabolism etabolism - Greek word; metabole – means “change” Metabolism is a process made up of; 1. Catabolism (is degradative to generate energy) 2. Anabolism (is synthetic that consume energy) Amphibolism and anabolic in nature. is also use for reactions which are both catabolic Catabolic.,E.g.the breaking down Anabolic., E.g. the (synthesis) of compounds, such as protein, CH2O.m nucleotide. building up of glucose to pyruvate by cellular , lipid and respiration (or for cellular activity).

  5. C Chemical rxn hemical rxns s of Metabolism of Metabolism Biochemical reactions Anabolic reaction In which absorbed nutrients are built up in to complex compounds that the body needs for its (synthesis of protein from amino acids). Catabolic reaction In which complex substances are broken down to simpler forms with release of energy for cellular activity (hydrolysis of glycogen to glucose). Catabolism release energy & Anabolism consumes energy.

  6. Catabolism (broken-down) occurs in three (3) stages; 1. Conversion of Complex Molecules into their Building Blocks; Polysaccharide are brokendown to monosaccahrides; lipid to free fatty acids and glycerols, and protein to amino acids. 2. Formation of Simple Intermediates; The building blocks produced are degraded to simple intermediates such as pyruvates and acetyl CoA`s. 3. Final Oxidation of Acetyl-CoA; Acetyl CoA is completely oxidized to CO2liberating NADH & FADH2that finally get oxidized to release large quantity of energy, as ATP.

  7. Anabolism (built-up) occurrence o During the periods of fasting (low food intake), carbohydrates restrictive diets, starvation, prolonged intense exercise., the ketone bodies are produced by the liver from fatty acids.- (Ketogenesis) oWhen high level of Glucose-6-phosphate are formed from the first reaction of glucose catabolism (Glycolysis), resulting from high carbohydrates food intake, the glucose are anabolised/synthesised to form what called glycogen.- (Glycogenesis) o Nucleotide metabolism (as in biosynthesis of both purine & pyrimidine). Liver & kidneys participate in glucose anabolism,as in case of body’s needs.

  8. M Metabolic Pathway etabolic Pathway The chemical reactions of metabolism are organised in to metabolic pathways. In which one chemical is transformed through a series of steps in to another chemical, each step being facilitated by a specific enzymes. See slide 4 (1) The metabolic pathways occur in a specific cellular location as mitochondria, cytosol, microsomes e.t.c.), and are controlled by different regulatory signals. (such The metabolic rate is partly controlled by the thyroid gland hormone and is affected by temperature and person’s activity. What is referred to as Basal Metabolic Rate (BMR) is the heat & energy required to maintain cellular function when the body is at rest.

  9. M Metabolic etabolic Reactions Reactions The biochemical reactions are mainly of four (4) types: 1.Redox reactions 2.Group transfer reactions The grouptransferintermediatesarecalledCoenzymes. Nucleotidesactsascoenzymesinmetabolic-group-transfer. 3.Rearrangement/ and Isomerization 4.Make/ and Break of carbon to carbon bond (C – C).

  10. M Metabolsm of Carbohydrate etabolsm of Carbohydrate  Major Groups of Carbohydrates Monosaccahrides; these are simples sugar that can be absorbed directely from the intestine. Disaccharides; aren’t directly absorbed from the intestine. On hydrolysis with specific enzymes,yield two molecules of monosaccharide. Polysaccharides; many carbohydrates in nature exist in the form of polusaccharides. They are more complex & aren’t easily absorbed in the body.

  11. M Metabolsm of Carbohydrate etabolsm of Carbohydrate  Major Pathway of Carbohydrate Metabolism 1. Glycolysis (E.M.Pathway);the oxidation of glucose to pyruvate and lactate. 2. Citric acid cycle (Kreb’s cycle);the oxidation of acetyl-CoA to CO2. 3. Glycogenesis;the formation of glycogen from glucose. 4. Glycogenolysis;the breakdown of glycogen to glucose. 5. Gluconeogenesis;the synthesis of glucose from non-CH2O.mprecursors. 6. Hexose monophosphate shunt (Pentose phosphate pathway);the oxidation of glucose alternative to glycolysis & TCA cycle, from it branches downstream of glucose 6-phosphate synthesis. For the production of a reduced coenzymes and pentose phosphate.

  12. M Metabolsm of Carbohydrate etabolsm of Carbohydrate  Major Pathway of Carbohydrate Metabolism 7. Uronic acid pathway; glucose is converted to glucuronic acid, pentose in some animals to ascorbic acid,not in man. 8. Galactose metabolism; the conversion of galactose to glucose and the synthesis of lactose. 9. Fructose metabolism; the oxidation of fructose to pyruvates and the relation between fructose and glucose metabolism. 10.Amino sugar and mucopolysaccharide metabolism;glucose is converted to glucuronic acid,pentose in some animals to ascorbic acid,not in man.

  13. M Metabolsm of Carbohydrate etabolsm of Carbohydrate  Entry of glucose into the cells In comparison,the concof glucose in plasma is much higher than in cells. Glucose doesn’t enter cells by simple diffusion. Has two (2) specific transfort system: 1. Insulin-independent erythrocytes and brain. transport system; this operate in hepatocytes, 2. Insulin-dependent transport system; this occur in muscle and adipose tissue. Glucose transporters: in recent year, atleast six GluT in the cell membrane have been identified. (GLUT-1 to GLUT-5 and GLUT-7) exhibits tissu specificity as in skeletal muscle and adipose tissue GLUT-4 is abundant, whereas GLUT-1 is abundant in erythrocytes. , Insulin increase the number..and promotes the GLUT-4`s activity.

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