Complex sugars (Polysaccharides)

They are carbohydrates which consist of group of monosaccharides, Complex sugars are also called Polysaccharides

Common properties of simple sugars:-

1- Insoluble in water

2- They have heavy molecular weights

3- They don't have any taste

Examples:-

1- Cellulose

2- Starch

3- Glycogen

(N.B: The polymers of each one of the previous complex sugars consist of glucose molecules bound together)

How to detect starch in substances

Starch changes the colour of iodine solution to blue

à They are biological macromolecules which are composed of carbon, oxygen and hydrogen. They divided into simple lipids (fats, waxes, oil), complex lipids (phospholipids) and derivative lipids (steroids)

à Lipids dissolve in non polar solvents such as carbon tetrachloride and benzene, but don't dissolve in polar solvents such as water

How to detect lipids in substances

à Sudan IV reagent is used to detect lipids, as lipids can dissolve in it changing its colour to red

The molecular structure of lipids

à Lipids are formed from 3 fatty acids bound to a glycerol molecule

à glycerol is an alcohol having 3 hydroxyl OH groups

Fig. (2) the structure of lipids

The importance of lipids

1- A source of energy: The energy released from lipids is more than that released from carbohydrates. Human body begins releasing energy from lipids when it runs out of carbohydrates.

2- The main component of cell membranes.

3- They make up 5% of the organic compounds forming living cells.

4- Some animals (polar bears, penguins, seals) store lipids under their skins to protect them from low temperatures.

5- They work as protective layers in some plants and animals.

6- Some of them (steroids) work as hormones

The classification of lipids

Simple lipids:-

à They are formed from the reaction of fatty acids with alcohols, they are classified according to the saturation of fatty acids into oils, fats and waxes.

Дата добавления: 2015-11-16