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CLASSIFICATION OF CARBOHYDRATES

CLASSIFICATION OF CARBOHYDRATES. STARCH GLYCOGEN CELLULOSE. MALTOSE LACTOSE SUCROSE. GLUCOSE GALACTOSE. FRUCTOSE. STARCH, GLYCOGEN & CELLULOSE. Polysaccharides are ubiquitous in nature.

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CLASSIFICATION OF CARBOHYDRATES

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  1. CLASSIFICATION OF CARBOHYDRATES STARCH GLYCOGEN CELLULOSE MALTOSE LACTOSE SUCROSE GLUCOSE GALACTOSE FRUCTOSE

  2. STARCH, GLYCOGEN & CELLULOSE Polysaccharides are ubiquitous in nature. They are called Homopolysaccharides, when made from same sugars and Heteropolysaccharides when made from different sugars. They can be linear or branched. Linear chains are made of α-1→4 bonds and branch is made of α-1→6 bonds

  3. STARCH • Is a storage polysaccharide in Plants • MADE OF α – GLUCOSE. • AMYLOSE – Linear, linked by α 1→ 4 bonds. [15 – 20%]. • AMYLOPECTIN – Branched, linked by α 1→ 6 bonds. [80 – 85%] • Branch point after every 30 Glc unit.

  4. GLYCOGEN • Storage polysacc in animals, highly branched. Similar to Amylopectin • Branch point every 8 – 12 Glc units • Has only 1 reducing end but many non-reducing ends

  5. CELLULOSE • Similar to Amylose, linear but made of β 1→ 4 bonds. • Very long chains – 15,000 – 20,000 Glc units • Can’t be digested because amylase recognises only ‘α’ bonds • Microorganism in gut Trichonympha secretes cellulase, which breaks down cellulose to short chain FA, a energy source

  6. METABOLISM Co-ordinated and specific reactions – organised as PATHWAYS… • PRIMARY FUNCTIONS: • Acquiring and Utilising Energy • Synthesis of structural components of cell eg Membrane • Growth & Development • Removal of waste products • GENERAL CHARACTERISTIC – of BIOCHEMICAL REACTIONS: • No. of reaction types are few – eg., Hydrolysis, Oxidation-reduction etc. • One enzyme usually catalyses only One reaction • Only a few important pathways inside cell – Glycolysis, Gluconeogenesis, • TCA cycle, Urea cycle, β-Oxidation etc. Anabolic and Catabolic Pathways

  7. CARBOHYDRATES METABOLISM GLYCOLYSIS • Glycolysis is a Amphibolic pathway • It occurs in Eukaryotes & Prokaryotes • It occurs in cytoplasm of cell • Total 10 reactions in 2 phases • End product depends on presence of O2

  8. Preparatory Pay Off

  9. ENERGETICS: 2 ATP 2 NADH = 6ATP FATE OF PYRUVATE

  10. GLUCONEOGENESIS PyruvateCarboxylase & PEP Carboxykinase function inside mitochondria

  11. CORI CYCLE

  12. HMP Shunt • AIM: • To produce NADPH, involved in biosynthetic reactions • To produce Ribose-5-P, a precursor for DNA synthesis

  13. HMP Shunt

  14. Phase I SUMMARY 1) Phase – I NADPH & Rib-5-P produced 2) Phase – II Transketolase & Transaldolase involved Phase II

  15. TCA CYCLE • Final pathway for oxidation of CHO, PTN & Lipid • Occurs in Mitochondrial Matrix • End product is Acetyl CoA • Series of dehydrogenation & decarboxylation rxns • Each cycle generates 12 ATP’s • It is amphibolic in nature FORMATION OF ACETYL COA: ENERGETICS: 2 NADH = 6 ATP

  16. TCA CYCLE ENERGETICS: 3 NADH = 9ATP 1 FADH2 = 2 ATP 1 GTP = 1 ATP ----------------------- TOTAL = 12 ATP ACONITASE CITRATE SYNTHASE ISOCITRATE dehydrogenase MALATE dhase GLUCOSE OXIDATION: GLYCOLYSIS = 8 ATP ACETYL CO-A = 6 ATP TCA CYCLE = 24 ATP ----------------------- TOTAL = 38 ATP KETO GLUTARATE dehydrogenase FUMARASE SUCCINATE dhase SUCCINATE THIOKINASE

  17. AMPHIBOLIC NATURE

  18. GLYOXYLATE CYCLE • MAIN FEATURES: • A modified form of TCA cycle • Occurs in Plants – during Germination stage • Helps to form Glucose from Lipid stores • Key enzymes – Isocitrate Lyase & Malate synthase • present inside Glyoxysomes. • Involves participation of 3 compartments inside cell; • glyoxysomes, mitochondria & cytosol

  19. GLYCOGENOLYSIS • Occurs from non-reducing end. • Takes place in muscle & liver • Glucose units enter glycolysis by the help of 3 enz:- • Glycogen phosphorylase • Glycogen debranching enzyme • Phosphogluco mutase GLYCOGEN GLUCOSE – 1 – P GLUCOSE – 6 – P

  20. GLYCOGENOLYSIS • Glycogen debranching enz reaction • Acts at a branch point when it’s 4 glc long. • Transfers a 3 glc unit from branch point to a • longer chain for p’lase action to continue • Last glc residue at branch removed as well Phosphogluco mutase reaction Glc-1-P → Glc-6-P

  21. GLYCOGENESIS • Starts when UDP-Glc & Glycogenin are available. • 4 enz involved:- • a) Phosphogluco mutase • Glc-6-P → Glc-1-P • b) UDP-glucose pyrophosphorylase • Glc-1-P + UTP → UDP-glc + PPi • c) Glycogen synthase – Transfers glc to non- • reducing end. Acts until branch is 11 unit • long • d) Glycogen branching enzyme – Transfers 6 • or 7 glc from a branch containing 11 glc units to • a more interior position creating a new • branch.

  22. GLYCOGENESIS c) Glycogen synthase – Transfers glc to non-reducing end. Acts until branch is 11 unit long

  23. GLYCOGENESIS d) Glycogen branching enzyme – Transfers 6 or 7 glc from a branch with 11 glc units to a more interior position creating a new branch.

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