This document is a comprehensive study guide on the biochemistry of lipids. It covers essential topics such as the classification of lipids, their functions, and the structure of fatty acids. The guide explains the differences between simple, complex, and derived lipids, along with their roles in biological systems. It also discusses the significance of essential fatty acids and the biochemical basis for their necessity in human health. The document includes detailed sections on triacylglycerols, phospholipids, and glycolipids, providing insights into their structures and functions. Additionally, it addresses lipid metabolism, the importance of lipoproteins, and the role of cholesterol in cellular processes. The content is structured to facilitate understanding for students and professionals in biochemistry and related fields. This study guide serves as an educational resource for those looking to deepen their knowledge of lipid biochemistry.
4- Biochemistry of Lipids
Introduction
Lipids (Greek: lipos-fat) may be regarded as
organic substances relatively insoluble in water,
soluble in organic solvents (alcohol, ether etc.),
actually or potentially related to fatty acids and
utilized by the living cells.
Unlike the polysaccharides, proteins and nucleic
acids, lipids are not polymers. Lipids are mostly
small molecules.
Classification
Lipids are broadly classified into simple, complex, derived and miscellaneous lipids,
which are further subdivided into different groups-
1 . Simple lipids : Esters of fatty acids with alcohols. These are mainly of two types
(a)Fats and oils (triacylglycerols):- These are esters of fatty acids with glycerol. The
difference between fat and oil is only physical. Thus, oil is a liquid while fat is a solid at
room temperature.
(b)Waxes:- Esters of fatty acids (usually long chain) with alcohols other than glycerol.
These alcohols may be aliphatic or alicyclic. Cetyl alcohol is most commonly found in
waxes.
2.Complex (Compound) lipids: These are esters of fatty acids with alcohols containing
additional groups such as phosphate, nitrogenous base, carbohydrate, protein etc. They
are further divided as follows
(a) Phospholipids: They contain phosphoric acid and frequently a nitrogenous base
This is in addition to alcohol and fatty acids.
(i) Glycerophospholipids:- These phospholipids contain glycerol as the alcohol e.g.,
Lecithin, Cephalin.
(ii)Sphingophospholipids:- Sphingosine is the alcohol in this group of phospholipids.
e.g., Sphingomyelin
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