LIPIDS Lipids are organic compounds which have the

Lipids are organic compounds, which have the following common properties: • They are esters

Classification Lipids are classified into three main groups: n n n 1) Simple Lipids:

Examples of lipid Classification SIMPLE LIPIDS Fats Waxes COMPOUND LIPIDS DERIVED LIPIDS PHOSPHOLIPID CHOLESTEROL

Classification of Lipids can also be divided into five categories, on the basis of

Functions of Lipids n n Source of energy Building blocks Carrier of vitamins (A,

Functions of Simple Lipids (Fats, Waxes) n n n They are neutral lipid Storage

Simple Lipids n Fats: Esters of fatty acids with glycerol. u. A fat in

Simple Lipids n n n Fats: They are found in nature in large quanti

Compound lipids n Compound lipids: These are classified again on the basis of prosthetic

Compound lipids n n Classification of Phospholipids. There are two types of phospholipids. 1.

Compound lipids n n n n Phospholipids: Glycerophospholipids u Examples: (i) Phosphatidyl ethanolamine (cephalin).

Compound lipids n n Glycolipids: They contain fatty acid, sphingosine, carbohydrate or carbohydrate derivative.

Compound lipids n n Lipoproteins: Lipoproteins are conjugated proteins, composed of core and surface.

Compound Lipids Lipoproteins: n n n Chylomicrons VLDL – Very low density lipoprotein IDL

Derived Lipids: Substances derived from the above groups by hydrolysis, e. g. Fatty acid,

Saturated Unsaturated Fatty Acids n n Saturated Fatty Acids: the SFA’s of a lipid

Saturated Unsaturated Fatty Acids Polyunsaturated Fatty Acids: more than one double bond in the

Derived Lipids Steroids and Cholesterol: Steroids are often found in association of lipids. They

Slides: 20

Download presentation

LIPIDS

Lipids are organic compounds, which have the following common properties: • They are esters of fatty acids or substances associated with them in nature. • Most of them are insoluble in water but soluble in fat solvents (non polar solvents) e. g. benzene, chloroform, acetone and ether.

Classification Lipids are classified into three main groups: n n n 1) Simple Lipids: They are esters of fatty acid with glycerol or higher alcohols. 2) Compound lipids: They are esters of fatty acid with one of the various alcohols and in addition, it contains other groups (nonlipid component). 3) Derived Lipids: Substances derived from the above groups by hydrolysis, e. g. fatty acid, glycerol, alcohol and cholesterol.

Examples of lipid Classification SIMPLE LIPIDS Fats Waxes COMPOUND LIPIDS DERIVED LIPIDS PHOSPHOLIPID CHOLESTEROL SPHINGOLIPIDS STEROID HORMONES Phosphingolipid FATTY ALDEHYDES KETONE BODIES GLYCOLIPID FAT SOLUBLE VITAMINS Cerebosides (ADEK) Gangliosides EICOSANOIDS Sulfatides Prostaglandin Leukotriene LIPOPROTEINS BILE ACIDS/SALTS GLYCEROL

Classification of Lipids can also be divided into five categories, on the basis of lipid function. 1. Energy storage lipids (triacylglycerols) 2. Membrane lipids (phospholipids) 3. Emulsification lipids (bile acids) 4. Messenger lipids (steroid hormones) 5. Protective coating lipids (biological waxes)

Functions of Lipids n n Source of energy Building blocks Carrier of vitamins (A, D, E, K)) Specialized functions u Antioxidant u Electron Transport Chain u Messenger/Signaling u Bone strength u Visual pigment

Functions of Simple Lipids (Fats, Waxes) n n n They are neutral lipid Storage in adipose tissues Body contouring Store of energy Insulation

Simple Lipids n Fats: Esters of fatty acids with glycerol. u. A fat in the liquid state is known as oil. u Fat is also called as triglyceride or triacylglycerol. n Waxes: Esters of fatty acids with monohydric long chain alcohols.

Simple Lipids n n n Fats: They are found in nature in large quanti ties. They are esters of fatty acids with glyc erol. They are the best reserve of food material in the human body. They act as a padding material for pro tecting internal organs. They act as insulator for the loss of body heat.

Compound lipids n Compound lipids: These are classified again on the basis of prosthetic group present in the lipid. n A. Phospholipids (phosphatides) n B. Glycolipids n C. Lipoproteins

Compound lipids n n Classification of Phospholipids. There are two types of phospholipids. 1. Glycerophospholipids - In this, glycerol is the alcohol group. 2. Sphingophospholipids – The alcohol present is sphingosine

Compound lipids n n n n Phospholipids: Glycerophospholipids u Examples: (i) Phosphatidyl ethanolamine (cephalin). (ii) Phosphatidyl choline (Lecithin). (iii) Phosphatidyl serine. (iv) Phosphatidyl inositol (v) Plasmalogens. (vi) Cardiolipins

Compound lipids n n Glycolipids: They contain fatty acid, sphingosine, carbohydrate or carbohydrate derivative. u Examples: n (i) Cerebroside n (ii) Ganglioside

Compound lipids n n Lipoproteins: Lipoproteins are conjugated proteins, composed of core and surface. Core of lipoprotein has triglycerides and cholesterol esters. Surface of lipoprotein has phospholipids, proteins and cholesterol.

Compound Lipids Lipoproteins: n n n Chylomicrons VLDL – Very low density lipoprotein IDL – Intermediate density lipoprotein LDL – Low density lipoprotein HDL – High density lipoprotein

Derived Lipids: Substances derived from the above groups by hydrolysis, e. g. Fatty acid, glycerol, alcohol and cholesterol. Fatty Acids: Fatty acids are aliphatic mono carboxylic acids that are mostly obtained from the hydrolysis of natural fats and oils. Fatty acids have the general formula R CO OH.

Saturated Unsaturated Fatty Acids n n Saturated Fatty Acids: the SFA’s of a lipid have no double bonds between carbons in chain. For example: u Acetic acid (2 carbon atoms) u Butyric acid(4 carbon atoms) u Plamitic acid (C 16) u Stearic acid (C 18) u Lignoceric acid (C 24)

Saturated Unsaturated Fatty Acids Polyunsaturated Fatty Acids: more than one double bond in the chain n Most common polyunsaturated fats contain the polyunsaturated fatty acids (PUFAs): These are linoleic acid, linolenic acid and arachidonic acid. n Unsaturated fats have lower melting points o o n Stearic (SFA) melts at 70 C, Oleic (PUFA) at 26 C n

Fatty Acids Found in Lipids

Derived Lipids Steroids and Cholesterol: Steroids are often found in association of lipids. They are compounds having special ring called cyclopentanoperhydrophenanthrene nucleus. For example, steroid hormone, bile acid, vitamin D Cholesterol is one of the important steroids present in the body. It is the precurser of various compounds such as vitamin D 3, bile acids, adrenocortical and sex hormones.