Lipids
Importance-
The lipids are important constituents of the diet because of their high energy value and also because of the fat soluble vitamins and the essential fatty acids found with the fat of the natural food stuffs. In the body, the fats serve as efficient source of energy which is stored in the adipose tissues. They also serve as an insulating material in the subcutaneous tissues and around certain organs. Fats combined with proteins(lipoproteins) are important constituents of the cell membranes and mitochondria of the cell.
Proteins, polysaccharides, DNA and RNA are macromolecules. Lipids are not generally classed as macromolecules, even though they share some of their features: for example most are synthesized as linear polymers of a smaller molecule (the acetyl group on acetyl- CoA), and their self assemble into larger structures (membranes). It is noteworthy that water and protein comprise most of the mass of both mammalian and bacterial cells.
Definition-
The lipids are a heterogeneous group of compounds related to fatty acids and include fats, oils, waxes and other related substances. These are oily or greasy organic substances, relativity insoluble in water and considerably soluble in organic solvents like ether, Chloroform and benzene. They are, thus hydrophobic in nature. These are variously called as lipins or lipoids. The latter term is, however sometimes used to refer "fat- like" substances which may not actually be related to the fatty acids. The term lipid was first used by the German biochemist Bloor in 1943 for a major class of tissue components and foodstuffs.
Chemically the fats are defined as the Esters of glycerol and fatty acids or as the triglycerides of fatty acids.
H2C-OH HOOC.C15.H31
|
HC-OH + HOOC.C15.H31 ==>
|
H2C-OH HOOC.C15.H31
(Glycerol) (Palmitic acid)
(1 mole) (3 mole)
H2C-OOC.C15.H31
|
HC-OOC.C15.H31 + 3H2O
|
H2C-OOC.C15.H31
Fatty acids-
Fatty acids are long chain organic acids having usually from 4 to 30 carbon atom; they have a a single carboxyl group and a long, nonpolar hydrocarbon 'tail', which gives most lipids their hydrophobic and oily or greasy nature. Fatty acids do not occur in free or uncombined state in cells or tissues but are present in covalently bonded form in different classes of lipids. Fatty acids which occur in natural fats are usually monocarboxylic and contain an even number of carbon atoms as these are synthesized from 2 Carbon units. These are usually straight chain derivatives. The chain may be saturated (containing only single bonds) or unsaturated (containing one or more double bonds). Some fatty acids may have hydroxyl group in the chain and still others may possess ring structure (cyclic fatty acids). Fatty acids are stored as an energy reserve (Fat) through and Easter linkage to glycerol to form triglycerides. If free, the carboxyl group of a fatty acids will be ionized.
_
O
|
/\/\/\/\/\/\/\/\/\/C=O
Importance-
The lipids are important constituents of the diet because of their high energy value and also because of the fat soluble vitamins and the essential fatty acids found with the fat of the natural food stuffs. In the body, the fats serve as efficient source of energy which is stored in the adipose tissues. They also serve as an insulating material in the subcutaneous tissues and around certain organs. Fats combined with proteins(lipoproteins) are important constituents of the cell membranes and mitochondria of the cell.
Proteins, polysaccharides, DNA and RNA are macromolecules. Lipids are not generally classed as macromolecules, even though they share some of their features: for example most are synthesized as linear polymers of a smaller molecule (the acetyl group on acetyl- CoA), and their self assemble into larger structures (membranes). It is noteworthy that water and protein comprise most of the mass of both mammalian and bacterial cells.
Definition-
The lipids are a heterogeneous group of compounds related to fatty acids and include fats, oils, waxes and other related substances. These are oily or greasy organic substances, relativity insoluble in water and considerably soluble in organic solvents like ether, Chloroform and benzene. They are, thus hydrophobic in nature. These are variously called as lipins or lipoids. The latter term is, however sometimes used to refer "fat- like" substances which may not actually be related to the fatty acids. The term lipid was first used by the German biochemist Bloor in 1943 for a major class of tissue components and foodstuffs.
Chemically the fats are defined as the Esters of glycerol and fatty acids or as the triglycerides of fatty acids.
H2C-OH HOOC.C15.H31
|
HC-OH + HOOC.C15.H31 ==>
|
H2C-OH HOOC.C15.H31
(Glycerol) (Palmitic acid)
(1 mole) (3 mole)
H2C-OOC.C15.H31
|
HC-OOC.C15.H31 + 3H2O
|
H2C-OOC.C15.H31
(Tripalmitin)
(1 mole)Fatty acids-
Fatty acids are long chain organic acids having usually from 4 to 30 carbon atom; they have a a single carboxyl group and a long, nonpolar hydrocarbon 'tail', which gives most lipids their hydrophobic and oily or greasy nature. Fatty acids do not occur in free or uncombined state in cells or tissues but are present in covalently bonded form in different classes of lipids. Fatty acids which occur in natural fats are usually monocarboxylic and contain an even number of carbon atoms as these are synthesized from 2 Carbon units. These are usually straight chain derivatives. The chain may be saturated (containing only single bonds) or unsaturated (containing one or more double bonds). Some fatty acids may have hydroxyl group in the chain and still others may possess ring structure (cyclic fatty acids). Fatty acids are stored as an energy reserve (Fat) through and Easter linkage to glycerol to form triglycerides. If free, the carboxyl group of a fatty acids will be ionized.
_
O
|
/\/\/\/\/\/\/\/\/\/C=O
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