Carbohydrates Definition :

are macromolecules, consists of Carbon, Hydrogen and Oxygen. H and O are found in

same proportion as in water (H2O).

Biological Significance of Carbohydrates:

1- Carbohydrates are the major source of Energy.

2- Stores energy in form of glycogen in liver and muscles.

3- Component of cellular membranes (as well as organelles membranes). e.g. cellulose of

plant cell wall, and Actin for cuticle of insects outer bodies.

Types of Carbohydrate in living organisms : can be divided into 3 types

1-Monosaccharides: The simplest form of carbohydrates.

• Monosaccharide exists in form of (unbranched )chain, or in cyclic form (ring).

• Molecular formula is (CH2O)n, where n is number of C atoms and =3,4,5,6,7.

• Monosaccharides are classified by the number of carbon atoms: Trios (3 carbon

atoms), tetrose(4), pentose (5), hexose(6), heptose(7).

• The cyclic (ring) form can be either a pentose (5) or hexose (6) only.

• e.g. Glyceraldehyde (Triose)( C3H6O3), Ribose and deoxyribose (pentose) found in

nucleic acids. Glucose and fructose (hexoses).

•2-Disaccharides:

Formed by binding of 2 units of monosaccharides by glycosidic bond (-O-) . Molecular

formula is C12H22O11.

* Maltose: 2 units of glucose , Joined together by glycosidic bond.

* Sucrose: Glucose + fructose ,Sucrose is table sugar we use as sweetener for food and

drinks.

* Lactose: Galactose + glucose, it is milk sugar.

3-Poly saccharides:

Large molecules composed of repeating units of monosaccharides. Molecular formula is

(C6H10O5)n, where n = number of monosaccharides units.

A-Polysaccharides can be divided chemically to:1- Homo-polysaccharides: consists of

one type of monosaccharides.

2- Hetero-polysaccharides: consists of different types of monosaccharides, e.g.

Hemicellulose (present along with cellulose in almost all plant cell walls.)- Hyaluronic

acid.( is a substance that is naturally present in the human body )

B- Polysaccharides can be divided according to function to:

Slide Features Reagents and dyes

(For read)

Object

Nutritional PolysaccharidesGlycogen in liver

Tissue parts stained red

indicate presence of glycogen

periodic acid

Schiff (PAS)

method

Glycogen )Animal

Starch(

Mucus in mucus gland

المخاطية المواداألمعاء mucusفي

in intestine

Tissue parts stained blue

indicate presence of

Mucoid substances.

Alcian blue

method

MucoidSubstance

)polysaccharide

derivatives (

Nutritional

PolysaccharidesStarch granules in

potatoe.

Starch granules stained dark.

Gieson Stain

Starch

Observation:

Sucrose solution with Fehling’s: Red brown precipitant

Sucrose solution with Silvanof: Bright red color

Results

•2-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 37˚C 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 for 15 min. Add 2 ml of Fehling reagent (A & B) , heat in boiling water bath

for 10 min. Results