Classification of Fatty acids

 Fatty acids

Fatty acids are carboxylic acid with hydrocarbon side chains. They are the simplest form of lipids and they are water soluble. They exist in the body either as free acids or fatty acyl esters such as triacylglycerol. The fatty acids are released from these lipids on hydrolysis by lipases.

Classification

Fatty acids may be divided into (i) saturated fatty acids and (2) unsaturated fatty acids.

1. Saturated fatty acids

These are fatty acids which donot contain double bonds. They have general formula CnH2n+1 COOH (Table 6.1).


 

2. Unsaturated fatty acid

These are fatty acids which contain double bonds. They have general formula (CnH2n-1 COOH). They are subdivided into

a) Monounsaturated fatty acid : These are fatty acids containing one double bond. (eg) Oleic acid.

CH3 (CH2)7CH = CH (CH2)7COOH

Oleic acid

2) Polyunsaturated fatty acid : These are fatty acids that contain more than one double bond.

(eg) linoleic acid, linolenic acid, arachidonic acid.

Importance

·           They act as energy stores and fuel molecules.

·           They are the major components of cell membrane.

 

3. Essential fatty acid (EFA)

The fatty acids that cannot be synthesised by the body and therefore should be supplied in the diet are known as essential fatty acids. Chemically they are polyunsaturated fatty acids (PUFA), namely linoleic acid, linolenic acid and arachidonic acid.

Structure

CH3 (CH2)4 CH = CH-CH2-CH=CH(CH2)7 COOH

Linoleic acid

CH3 (CH2)4 CH = CH-CH2-CH=CH -CH2-CH = CH(CH2)7 COOH

Linolenic acid

CH3 (CH2)4 CH = CH-CH2-CH=CH -CH2-CH = CH-CH2-CH=CH-(CH2)3 COOH

Arachidonic acid


Functions

·           EFAs are requried for the membrane structure and functions.They are necessary for the maintenance of growth, reproduction and good health.

·           They are important for the transport of cholesterol, formation of lipoportein and prevention of fatty liver.

·           They serve as precursor for prostaglandin biosynthesis.

·           They prolong clotting time and increase fibrinolytic activity.

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