Metabolism of Carbohydrate Part -I.pptx

Metabolism is the chemical reactions in the body's cells that change food into energy.
Our bodies need this energy to do everything from moving to thinking to growing.

1. Mr. Abhijit Bhoyar Assistant Professor Department of Child Health Nursing Metabolism CARBOHYDRATE Part-I

2. Specific Learning Objectives At the end of the lecture, the students will be able to Define the metabolism. List down categories of metabolism Enumerate basic functions of metabolism. Explain the biomedical importance of Glucose. Describe the metabolism of carbohydrates. Explain the major pathways of carbohydrate metabolism.

3. Introduction Hundreds of reactions simultaneously take place in a living cell, in a well-organized and integrated manner. The entire spectrum of chemical reactions, occurring in the living system, are collectively referred to as metabolism.

4. Definition of Metabolism

5. A metabolic pathway (or metabolic map) It constitutes a series of enzymatic reactions to produce specific products. The term metabolite is applied to a substrate or an intermediate or a product in the metabolic reactions .

6. Metabolism is broadly divided into two categories CATABOLISM ANABOLISM Metabolism

7. Amphibolism The term amphibolism is also in use for reactions which are both catabolic and anabolic in nature.

8. Catabolism occurs in three stages Conversion of complex molecules into their building blocks : Polysaccharides are broken down to monosaccharides, Lipids to free fatty acids and glycerol Proteins to amino acids.

9. Cont…. 2. Formation of simple intermediates : The building blocks produced in stage (1) are degraded to simple intermediates such as pyruvate and acetyl CoA. These intermediates are not readily identifiable as carbohydrates, lipids or proteins. A small quantity of energy (as ATP) is captured in stage 2.

10. Cont…. 3. Final oxidation of acetyl CoA : Acetyl CoA is completely oxidized to CO2, liberating NADH ( Nicotinamide Adenine Dinucleotide ) and FADH2 ( Flavin adenine dinucleotide) that finally get oxidized to release large quantity of energy (as ATP ). Krebs cycle (or citric acid cycle) is the common metabolic pathway involved in the final oxidation of all energy-rich molecules. This pathway accepts the carbon compounds (pyruvate, succinate etc.) derived from carbohydrates, lipids or proteins.

11. Basic functions of metabolism

12. Biomedical Importance Of Glucose Glucose is a major carbohydrate It is a major fuel of tissues It is converted into other carbohydrates Glycogen for storage. Ribose in nucleic acids. Galactose in lactose of milk.

13. Cont…. They form glycoproteins & proteoglycans They are present in some lipoproteins (LDL) . Present in plasma membrane.

14. Metabolism of Carbohydrates It is a fundamental biochemical process that ensures a constant supply of energy to living cells. The most important carbohydrate is glucose, which can be broken down via glycolysis , enter into the Kreb's cycle and  oxidative phosphorylation  to generate ATP.

15. Cont…. Carbohydrates are the major source of energy for the living cells. As such, carbohydrates are the first cellular constituents , synthesized by green plants during photosynthesis from carbon dioxide and water, on absorption of light. Thus , light is the ultimate source of energy for all biological processes.

16. Cont…. The monosaccharide glucose is the central molecule in carbohydrate metabolism since all the major pathways of carbohydrate metabolism are connected with it. Glucose is utilized as a source of energy , it is synthesized from non-carbohydrate precursors and stored as glycogen to release glucose as and when the need arises. The other monosaccharides important in carbohydrate metabolism are fructose, galactose and mannose .

17. Cont…. The fasting blood glucose level in normal individuals is 70-100 mg/dl (4.5-5.5 mmol /l ). Liver plays a key role in monitoring and stabilizing blood glucose levels. Thus liver may be appropriately considered as glucostat monitor.

18. Major pathways of carbohydrate metabolism Glycolysis (Embden-Meyerhof Parnas) EMP Pathway : Glycolysis is the process in which glucose is broken down to produce energy. The oxidation of glucose to pyruvate and lactate. Citric acid cycle (Krebs cycle or tricarboxylic acid cycle) : The oxidation of acetyl CoA to CO2. Krebs cycle is the final common oxidative pathway for carbohydrates, fats or amino acids, through acetyl CoA.

19. Cont…. Gluconeogenesis : The synthesis of glucose from non-carbohydrate precursors (e.g. amino acids, glycerol etc.). Glycogenesis : The formation of glycogen from glucose. Glycogenolysis : The breakdown of glycogen to glucose. Hexose monophosphate shunt (pentose phosphate pathway or direct oxidative pathway) : This pathway is an alternative to glycolysis and TCA cycle for the oxidation of glucose (directly to carbon dioxide and water ).

20. Cont…. Uronic acid pathway : Glucose is converted to glucuronic acid, pentoses and, in some animals, to ascorbic acid (not in man). This pathway is also an alternative oxidative pathway for glucose . Galactose metabolism : The pathways concerned with the conversion of galactose to glucose and the synthesis of lactose.

21. Cont…. Fructose metabolism : The oxidation of fructose to pyruvate and the relation between fructose and glucose metabolism. Amino sugar and mucopolysaccharide metabolism : The synthesis of amino sugars and other sugars for the formation of mucopolysaccharides and glycoproteins.

22. Summary So far today we have discussed definition, categories of metabolism, basic functions of metabolism, biomedical importance of Glucose, metabolism of carbohydrates and major pathways of carbohydrate metabolism.

23. Expected Questions LAQ Describe the metabolism of carbohydrates . SAQ Explain the biomedical importance of Glucose. Describe the metabolism of carbohydrates. Explain the major pathways of carbohydrate metabolism .

24. Cont.…. Very Short Define the metabolism. List down categories of metabolism Enumerate basic functions of metabolism.

25. Jacob Anthikad, Biochemistry for nurses. Pankaja Naik, Essentials of Biochemistry. Satyanarayan, Essentials of Biochemistry. A. C. Deb, Biochemistry. References