CLASSIFICATION OF CARBOHYDRATES CARBOHYDRATE MONOSACCHARIDE ALDOSE GLUCOSE GALACTOSE

CLASSIFICATION OF CARBOHYDRATES CARBOHYDRATE MONOSACCHARIDE ALDOSE GLUCOSE GALACTOSE KETOSE FRUCTOSE DISACCHARIDE MALTOSE LACTOSE SUCROSE POLYSACCHARIDE STARCH GLYCOGEN CELLULOSE

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

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.

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

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

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: Ø No. of reaction types are few – eg. , Hydrolysis, Oxidation-reduction etc. Ø One enzyme usually catalyses only One reaction Ø Only a few important pathways inside cell – Glycolysis, Gluconeogenesis, TCA cycle, Urea cycle, β-Oxidation etc. Anabolic and Catabolic Pathways

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 O 2

Pay Off Preparatory

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

GLUCONEOGENESIS Pyruvate Carboxylase & PEP Carboxykinase function inside mitochondria

CORI CYCLE

HMP Shunt AIM: 1. To produce NADPH, involved in biosynthetic reactions 2. To produce Ribose-5 -P, a precursor for DNA synthesis

HMP Shunt

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

TCA CYCLE • • • Final pathway for oxidation of CHO, PTN & Lipid Occurs in Mitochondrial Matrix End product is Acetyl Co. A 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

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

AMPHIBOLIC NATURE

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

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

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

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 nonreducing 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.