chemistryof carbohydrate

Unit 1: Chemistry of Carbohydrate (9) hrs.
•Definition of carbohydrate.
•Classification, Mono, oligo and Polysaccharide.
•Chemical properties of Carbohydrate.
•Metabolism of Carbohydrate.
-Glycogensis
-Glycogenolysis
-Glycolysis
-Kreb Cycle
•Metabolic disorder of carbohydrate metabolism.
-Diabetes mellitus.

Summary: Carbohydrates are organic substances of polyhydroxy aldehyde or ketone derivatives. They are classified into
monosaccharide (glucose), disaccharides (sucrose), oligosaccharides (maltotriose) and polysaccharides. Polysaccharides are
of homopolysaccharides (starch, glycogen, cellulose and inulin) and heteropolysaccharides (hyaluronic acid, dermatan sulfate,
keratin sulfate and heparin). Carbohydrates form stereoisomers like D and L-sugars are referred to as enantiomers (mirror
images of each other). Carbon 1 of sugars is anomeric carbon atom (a-D glucose and b-D-glucose). The isomers formed due to
variations in the configuration of –H and –OH around a single carbon atom in a sugar molecule is called as epimers (mannose
and galactose are 2 and 4 epimers of glucose respectively). Sucrose is nonreducing and also called invert sugar.
Carbohydrates are the essential component of diet. The pancreatic and intestinal enzymes hydrolyze the
polysaccharides to simple monosaccharides. The galactose and glucose are absorbed very rapidly by the active process. Fructose
and mannose are absorbed by a Na+ independent facilitative diffusion. Glucose is the main source of energy to our body.
Glucose undergoes glycolysis to generate the energy in the form of ATP. Puruvate formed in glycolysis converted to acetyl
CoA which enters TCA cycle to generate large number of ATPs. The acetyl CoA is also required to synthesize cholesterol, fatty
acids, ketone bodies and steroid hormones. Insulin stimulates the glycogenesis through which excess glucose absorbed will
be converted to glycogen and stored in muscle and liver. Hyperglycemic hormones stimulate the glycogen breakdown when
glucose level goes down. Glycogenesis and glycogenolysis are regulated by glycogen synthase and glycogen phosphorylase
respectively. Hyperglycemic also hormones stimulate the gluconeogenesis. Hexose monophosphate pathway generates large
number of NADPH which is required to maintain the active reduced glutathione peroxidase and to synthesize fatty acids.
Pathway also produces ribose sugars which is the essential component for the synthesis of nucleic acids. The insulin deficiency
results in diabetes mellitus which are of two types: insulin dependent diabetes mellitus and noninsulin dependent diabetes
mellitus. The major complications of diabetes are retinopathy, nephropathy and neuropathy. The fasting blood glucose and
HbA1c are used to detect and monitor diabetes. Oral glucose tolerance test is preferred to detect the diabetes mellitus during
pregnancy and other conditions.