Lipids are a group of different types of organic compounds. They contain carbon-hydrogen and oxygen other elements such as nitrogen phosphorus may also be present in lipids. Most lipids are nonpolar and they are insoluble in water and are hydrophobic in nature. They are easily soluble in organic solvent such as ether acetone petrol and alcohol etc. Lipids are classified into various types such as acyl glycerol phospholipids, waxes & terpenoids.
The first and most important types of lipids include acylglycerol which is composed of glycerol and fatty acids. The most common acyl glycerol are triglycerides containing one glycerol molecule and three fatty acids. Glycerol is a three-carbon compound to each carbon hydroxyl group is attached hydroxyl group is polar and therefore glycerol is soluble in water. The acid portion of 3 fatty acid reacts with three hydroxyl group of the glycerol so that the triglyceride and three water molecules are formed this reaction is called condensation reaction. The triglyceride molecule can be e hydrolyzed into its components such as glycerol and 3 fatty acids.
Fatty Acids consist of a long hydrocarbon chain with the carboxyl group. Most of the fatty acid in the cell contains 16 to 18 carbon atoms per molecule. Fatty acids may be saturated or unsaturated the saturated fatty acids have no double bond between the carbon atoms search molecules cannot accommodate anymore hydrogen. If added to the unsaturated fatty acids have one or more double bonds between the carbon atoms and search molecules the number of hydrogen is less than two per carbon atom. So after removing the double bond, we can accommodate the hydrogen atom which they are lacking unsaturated fatty acids are usually liquid at room temperature the triglycerides have high calorific value we can give double energy as compared to per gram of carbohydrates.
Another most important part of lipids includes phospholipids which are composed of one glycerol molecule and 2 fatty acids and a phosphoric acid molecule usually linked to some nitrogen group. Phospholipid molecule has two parts one is hydrophobic and the other is hydrophilic. The head is normally polar in nature, therefore, it is soluble in water. While the tail is hydrophobic in nature and that’s why they are unable to to get reacted with water. The phospholipids arrange themselves in a double layer in the presence of water in the plasma membrane of the cell.
Another most important type of lipids include waxes which are normally formed by a long chain of fatty acid bonded to a long-chain alcohol. They are solid at room temperature because they have a high melting point they are hydrophobic in nature. They are stable compounds and are resistant to the degradation of this former waterproof layer on the surface of some plants on their leaves also on fruits in order to avoid the rate of water loss water barrier. Waxy layer generally covers the body of some animals such as sheep and insects as well.
Last but not the least the most important type of lipids include steroids which do not contain fatty acid and they are usually formed of 17 carbon atoms cholesterol is the chief representative example of steroid so these are the parts of lipids which are most important human body in such a way that they can produce large amount of energy as compared to carbohydrates and other energetic sources.