Lab 2 Carbohydrates

Carbohydrates are macromolecules, consists of Carbon, Hydrogen and Oxygen. H and O are found in same proportion as in water (H2O).

How carbohydrates can be form? in the plant cells and tissues from their natural sources (CO2 and H2O) Photosynthesis CHLOROPLASTS + LIGHT carbohydrates 6H2O+6CO2 C6H12O6 +6O2

Biological Significance of Carbohydrates: 1- Carbohydrates are the major source of Energy. 2- Component of cellular membranes and organelles membranes). -cellulose of plant cell wall -cuticle of insects outer bodies 3- Stores in form of glycogen and starch

Carbohydrates in living organisms can be divided into 3 types: Monosaccharides: The simplest form of carbohydrates. Molecular formula is (CH2O)n, where n is number of C atoms and =3,4,5,6 or 7. Monosaccharides exists in form of unbranched chain, or in cyclic form (ring).

Monosaccharides are classified by the number of carbon atoms: Triose =3 carbon atoms tetrose =4 carbon atoms pentose =5 carbon atoms Hexose =6 carbon atoms Heptose =7 carbon atoms The cyclic (ring) form can be either a pentose or hexose only. Glyceraldehyde (Triose) Ribose and deoxyribose (pentose) Glucose and fructose (hexoses(

Disaccharides: Maltose: Formed by binding of 2 units of monosaccharides by glycosidic bond (-O-) . Molecular formula is C12H22O11. 2C6H12O6 6H2O C21H22O11 Maltose: 2 units of glucose Sucrose: Glucose + fructose Lactose: Galactose + glucose

Polysaccharides can be divided chemically to: Large molecules composed of repeating units of monosaccharides. Molecular formula is (C6H10O5)n, where n = number of monosaccharides units. Polysaccharides can be divided chemically to: 1- Homopolysaccharides: consists of one type of monosaccharides. 2- Heteropolysaccharides: consists of different types of monosaccharides, e.g. Hemicellulose- Hyaluronic acid.

2- Nutritional Polysaccharides 1- Structural Polysaccharides Polysaccharides can be divided according to function to: 2- Nutritional Polysaccharides 1- Structural Polysaccharides Glycogen (animal starch) units of glucose linked by α- glycosidic bond. Branched. Cellulose units of glucose linked by β- glycosidic bond, unbranced and linear. Starch units of glucose linked by α- glycosidic bond. Unbranched and spiral (helical) called Amylose. Or banched called Amylopectine. Chitin units of acetyl-glucose amine. Forms the outer skeleton of insects and crustaceans.

Nutritional Polysaccharides Glycogen in liver

Mucus in mucus gland

Mucus in intestine

Starch granules in potatoes

Detection of Carbohydrates Detection of Monosaccharides: Detection of Glucose and Fructose 1- In test tube, put 5 ml of sucrose solution (1%) , add 5 drops of HCl 2- Heat mixture of sucrose preparation in boiling water for 5 minutes. 3- Add 1 ml of NaOH solution 4- To detect Glucose (Fehling reaction): In test tube mix 1 ml of Fehling A + 1 ml Fehling B, then add 5 drops of sucrose preparation and heat over flame for 5 minutes. 5- To detect fructose (Silvanof reaction) : In test tube put 5 drops of sucrose preparation + 2 ml of silvanof reagent Observation: Sucrose solution with Fehling’s: ………………………… Sucrose solution with Silvanof: …………………………..

Effect of Invertase enzyme on Sucrose Digestion and Hydolysis: 1- Prepare invertase enzyme extract by grinding 10 gm of yeast with 5 ml distilled water and table sugar. 2- In test tube, put 2 ml of sucrose solution (2%) + 2 ml of Fehling reagent (1ml of Fehling A and 1 ml of B), heat in boiling water bath for 6 min. 3- In new test tube, put 2 ml of sucrose solution + 2 ml of invertase extract and mix well. Then put in 37˚C for 15 min. Add 2 ml of Fehling reagent (A & B) , heat in boiling water bath for 10 min.