LIPIDS and their classification

DEFINITION

The lipids are a heterogeneous group of compounds, including

fats, oils, steroids, waxes, and related compounds.

They have the common property of being

(1) relatively insoluble in water.

(2) soluble in nonpolar solvents such as ether and chloroform.

(3)related more by their physical than by their chemical properties.

SOURCES

ANIMALAnimal fat ,meat ,butter ,milk ,cream ,ghee ,egg yolk ,liver

PLANTVegetable oil

CLASSIFICATION1

SIMPLE

LIPIDS2

COMPOUND

LIPIDS

3

DERIVED

LIPIDS

SIMPLE LIPIDS

Esters of fatty acids with various alcohols.

FATSEsters of fatty acids with glycerol.

Oils are fats in liquid state.

WAXESEsters of fatty acids with higher molecular weight monohydric alcohols.

COMPOUND LIPIDS

Esters of fatty acids containing groups in addition to an alcohol and a fatty acid.

PHOSPHOLIPIDSLipids containing, in addition to fatty acids and an alcohol, a phosphoric acid residue.

GLYCOLIPIDSLipids containing a fatty acid, sphingosine, and carbohydrate.

OTHER LIPIDSSulfolipids, amino lipids, lipoproteins

PHOSPHOLIPIDS

GLYCOLIPIDS

DERIVED LIPIDS

• THESE are hydrolytic products of above mentioned compounds

• Lipoprotein

• Steroid

• Hormone

• Fatty acids

• Prostaglandin

• Glycerol

• Ketone bodies

• Aldehyde

• Fat soluble vitamins

FUNCTIONS OF LIPIDS Storage form of energy(9kcal/g)

Important dietary constituents

Components of fat-soluble vitamins

Stored in adipose tissue , serves as a thermal insulator

LIPOPROTEINS transport lipids in the blood.

Role in pathophysiology of diseases e.g. obesity, diabetes mellitus, atherosclerosis

Role in nutrition and health.

Structural components of biomembranes.

FUNCTIONS OF LIPIDS

Metabolic regulator.

Improve taste and palatability of food.

Give shape and contour to body.

Act as surfactant, detergents, emulsifying agents.

Cushioning effect to internal organs.