BRIEF REVIEW OF LIPIDS

Lipids are actually diverse nature compounds which are related to fatty acids. They are water fearing compounds and are soluble compounds organic compounds like alcohol, ether, chloroform, benzene etc. Lipids are hydrophobic compounds and are components of cellular layers.

Remarkable features of lipids include that they provide wadding against atmospheric stress i.e. heat and cold. As they are hydrophobic so they act as water proof material. Lipids can also store energy. They can almost store double amount of energy as that of carbohydrates. The reason for this double storage of energy in lipids is they have high percentage of C-H bonds and low amount of oxygen. In some plants there is cuticle, a supplementary protective membrane is made up of waxes which is one of the types of lipids. Exoskeleton of insects is also made up of waxes. 

Classification of Lipids:

Lipids are categorized as acylglycerols, waxes, phospholipids, sphingolipids, glycolipids and terpenoids including carotenoids and steroids. Let’s get a succinct review of some of the types of lipids.

So, Lipids are group of naturally occurring molecules.

Acylglycerols:

Acylglycerols are esters of fatty acids. Esters are those compounds which are formed by reaction of alcohols and acids and a water molecule is released. Hydrogen (H) and hydroxyl (OH^-) is released from acid and alcohol respectively and combine to form water (H₂O). Composition of Acylglycerol is fatty acids and glycerol. The most common acylglycerol is triacylglycerol. Triacylglycerol is also called neutral lipid.

Waxes:

cuticle, a waxy layer on leaf

Waxes also fall in lipid’s classification. Waxes are generally found as a protective covering on fruits and leaves. Exoskeleton of insects is also made up of waxes. The reason for waxed coating on plants is they prevent extra water loss and abrasive damage. Chemical composition of waxes includes mixture of long chain alkanes, alcohols, ketones and esters of extended chain fatty acids.

Phospholipids:

Phospholipids are usually found in bacterial, animal and plant’s membrane. These are derived from phosphatidic acid. Choline, ethanolamine and serine are important components of phospholipids.

Terpenoids:

Terpenoids are composed of single repeating units called isoprenoids units. Condensation of isoprenoids units give rise to many useful compounds such as rubber, steroids etc. Terpenoids can also store energy. Applications of terpenoids include insulation and protection from water loss.

Saturated and Unsaturated fatty acids:

It is our common observation that some fatty acids (oils) are liquid at room temperature and some fatty acids (fats) are solid at room temperature. Oils are called unsaturated fatty acids and fats are called saturated fatty acids. Both are lighter than water. Plant fats are liquid, while animal fats are solid at room temperature.

plant fats are liquid

animal fats are solids