Catabolism of Carbohydrates_sugarsss.pptx

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1. Catabolism of carbohydrates SUBMITTED TO : SUBMITTED BY : Dr. Ashish Sachan Rechal Kerketta Roll no.-27 M.Sc. Life Sciences,Semester I

2. INTRODUCTION Carbo hydrates are organic molecules. Carb ohydrates are one of the main types of nutrients. They are the most important source of energy for our body. Our digestive system changes carbohydrates into glucose ( Blood sugar ). Then the body uses the sugar as energy for the cells, tissues and organs. There are two types of Carbohydrates:- Simple carbohydrates Example Monosaccharides - glucose, fructose, galactose Disaccharides - sucrose, lactose, matlose Complex carbohydrates Examples: starch, cellulose

3. Metabolism Metabolism refers to all the biochemical reactions that occur in a cell or organism. Metabolism includes:- Catabolism Anabolism Catabolism is the set of metabolic pathways that break down molecules into smaller unites that are either oxidised to release energy used in other anabolic reactions. Anabolism is the set of metabolic pathways that construct molecules from smaller units . These reactions require energy and known as an endergonic process.

4. Bacterial Metabolism The study of bacterial metabolism focuses on the chemical diversity of substrate oxidisation and dissimilation reaction ( reaction by which substrate molecules are broken down), which normally function in bacteria to generate energy.

5. Catabolism of Carbohydrates Glucose is the most common substrate used for studying heterotrophic metabolism. The complete oxidation of glucose may involve three fundamental biochemical pathways:- Glycolytic or Embden-Meyerhof- Parnas pathway Kerbs cycle (citric acid cycle or tricarboxylic acid cycle) Electron transport oxidations coupled to oxidative phosphorylation

6. Glycolysis For bacteria, eukaryotes and most archaebacteria , glycolysis is the most common pathway for the catabolism of glucose. It produces energy, reduced electron carrier and precursor molecules for cellular metabolism. Glycolysis takes place in the cytoplasm of prokaryotic and eukaryotic cells.

7. Overall, in this process of glycolysis, the net gain from breakdown of a single glucose molecule is:- 2 ATP molecule 2 NADH molecule 2 Pyruvate molecule

8. Other glycolytic pathway Some prokaryote use alternative glycolytic pathways. These are:- Entner Doudoroff (ED) pathway Pentose Phosphate Pathway

9. Entner Doudoroff Pathway The highly oxidative Azotobacter and most Pseudomonas species, utilize the ED pathway for glucose catabolism. These organism lack the enzyme phosphofructokinase and hence cannot synthesize fructose 1,6-diphosphate, a key intermediate compound in the glycolytic pathway

10. Pentose Phosphate Pathway Also called Hexose Monophosphate Shunt. All Cyanobacteria , Acetobacter suboxydane & A. xylium have only Pentose Phosphate Pathway.

11. Transition Reaction Glycolysis produces pyruvate which can be further oxidised to capture more energy. Pyruvate enter the next oxidative pathway. In transition reaction, a multi enzyme complex converts pyruvate into one acetyl group and one carbondioxide . In this process, one molecule of NADH is formed.

12. Tricarboxylic Acid (TCA) Cycle/Krebs Cycle/Citric Acid Cycle Acetyl CoA enters the TCA cycle. Citrate is oxidised in a series of steps resulting in the formation of 3 NADH, 1 FADH 2 & 1 ATP or GTP. TCA Cycle enzymes are widely distributed among microorganisms. In prokaryotes, they are located in the cytoplasmic matrix. In eukaryotes, they are found in the mitochondrial matrix.

13. Electron Transport Chain & Oxidative Phosphorylation The location of ETC is the inner mitochondrial matrix in eukaryotes while cytoplasmic matrix in prokaryotes.

14. Monosaccharide Catabolism

15. Disaccharide Catabolism

16. Polysaccharide Catabolism