Fatty Acids – Definition, Classification, Functions, Essential Fatty Acids
Definition of Fatty Acids:
Fatty acids may be defined as organic acid that occur in a natural triglyceride and is a monocarboxylic acid ranging from C4 to C28 atoms in straight chains and will usually have either a saturated hydrocarbon chain or may contain from one to six double bonds.
Classification of Fatty Acids:
1) Saturated Fatty Acid: Contain no double bond, chain is saturated.
e.g. Butyric acid (4), Caproic acid (6) Caprylic acid (8) Capric acid (10), Laurie acid (12), Myristic acid (14), Palmitic acid, (16) Stearic acid (18), Arachidic acid (20) Behenic acid (22) Lignoceric acid (24), Cerotic acid (26) Montanic acid (28) [Figures in the bracket is number of carbons].
2) Unsaturated Fatty Acid: Contain one or more double bond in chain and degree of unsaturation depends on the no of double bond present in it.
Sub classified on the basis of degree of unsaturation.
a) Monoethenoid Acids: Contain one double bond e.g. oleic acid, palmitoleic acid
b) Diethenoid Acids: Contain two double bond e.g. Linoleic acid.
c) Triethenoid Acid: Contain three double bond e.g. Linolenic acid Eleostearic acid
d) Tetraethenoid Acids: Contain four double bond e.g. Arachidonic acid.
3) Branched Chain Fatty Acids: Contain hydroxyl group in chain of fatty acid
4) Cyclic Fatty Acid: Posses ring structure e.g. chaulmoogric acid and hydnocarpic acid
Functions of Fatty Acids:
1) Source of energy in stored forms
2) Solubilize vitamins like A, D, E, and K.
3) Building units of majority of lipids
4) Constituent of phospholipids
Essential Fatty Acids:
Fatty acids which cannot be synthesized by the cell of the body must be obtained from other source. Essential fatty acids are linoleic, linolenic and arachidonic acid.