2.4 Lipids

Fats and their derivatives are collectively called lipids. Fats are compounds containing fatty acids and glycerol. They are composed of carbon, hydrogen and oxygen, but less oxygen than that in carbohydrates. Fatty acids are long chains of CH₂ groups with terminal methyl and carboxyl groups with general formula CH₃[CH₂]n-COOH, while glycerol molecule contains a chain of three carbon atoms and has a formula C₃H₆O₃. In the formation of fat, three molecules of fatty acids are combined with three-OH groups on one molecule of glycerol, with removal of 3 molecules of water which is represented as follows :

There are mainly three types of lipids . the simple lipids, commonly known as fats and oils, the compound lipids such as phospholipids and glycolipids which on hydrolysis yield not only alcohol and fatty acids but also other compounds and derived lipids such as steroids which include cholesterol, Vitamin D, estrogen , testosterone, cortisol, etc. Lipids are practically insoluble in water but are soluble in organic solvents like chloroform, ether and benzene.

Fats stored in cells are usually clear oil droplets called globules. Because fats do not dissolve in water, animals store fat in large clear globules in the cells of adipose tissue. The enzyme lipose breaks down fats into fatty acids and glycerol which can be furthur broken down to produce energy.

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Table of Contents

2.0 - Introduction
2.1 Structural Organization and Chemical Basis Of Life
2.2 Organic Compounds
2.3 Nucleotides and Nucleic Acid
2.4 Lipids

Chapter 3