LipidLipid

The function of lipidThe function of lipid    Lipids are a class of biological molecules defined by low solubility in water and high

solubility in nonpolar solvents.

Function:

Energy

membrane

5.· Fatty Acids5.· Fatty Acids

Fatty acids are either saturated (all carbon-carbon bonds are single bonds) or unsaturated

(with one or more double bonds in the hydrocarbon chain). If a fatty acid has a single double bond, it is said to be monounsaturated, and if it has more than one, polyunsaturated.

A list of the most abundant fatty acids (M table 10.1)A list of the most abundant fatty acids (M table 10.1)

Composition of Composition of natural fats (M natural fats (M

table 10.2)table 10.2)

5.2 Triacylglycerol: the fat 5.2 Triacylglycerol: the fat tristearin (M10.2)tristearin (M10.2)

Polar Bears Use Triacylglycerols to Survive Long Periods of Fasting

Whales and Arctic mammals rely on body fat for both insulation and energy reserves.

Glycerophospholipids Glycerophospholipids

A 1,2-diacylglycerol that has a phosphate group esterified at carbon atom 3 of the

glycerol backbone is a glycerophospholipid, also known as a phosphoglyceride or a

glycerol phosphatide

Phosphatidic acid, the parent compound for glycerophospholipids

The Most Common The Most Common Phospholipids Phospholipids

Phosphatidic acidPhosphatidic acid

phosphatidyleth-phosphatidyleth- anolamine,anolamine, is is diphosphatidylglyceroldiphosphatidylglycerol

Structures of several glycerophospholipids and space-filling models of phosphatidylcholine, phosphatidylglycerol, and phosphatidylinositol.

A scheme of a micelle A scheme of a micelle and a membrane and a membrane

(M10.5)(M10.5)

Soaps and detergents (M p 319)Soaps and detergents (M p 319)

SDS

Triton X-100

Phospholipids (M 10.6)Phospholipids (M 10.6)

The hydrophilic The hydrophilic groups of groups of

phospholipids phospholipids (M10.7)(M10.7)

Structure Structure of a of a

typical typical membrane membrane (M10.10)(M10.10)

GlycerophospholipidGlycerophospholipid Degradation:Degradation:

One of the Effects of Snake Venoms The venoms of poisonous snakes contain (among

other things) a class of enzymes known as phospholipases, enzymes that cause the

breakdown of phospholipids.

Ether Glycerophospholipids Ether Glycerophospholipids

Ether glycerophospholipids possess an ether linkage instead

of an acyl group at the C-1 position of glycerol

A 1-alkyl 2-acyl-phosphatidylethanolamine (an ether glycerophospholipid).

The structure of 1-alkyl 2-acetyl-phosphatidylcholine, also known as

platelet activating factor or PAF

The structure and a space-filling model of a choline plasmalogen. 

5.4 Other lipids5.4 Other lipids

Sphingolipids

Waxs

Terpens

Cholesterol

Steriod hormone

Sphingolipids often a hydrocarbon R group is Sphingolipids often a hydrocarbon R group is attached to the NHattached to the NH22 as in ceramide as in ceramide

General structure of General structure of glycosphingolipid (M glycosphingolipid (M

p323)p323)

A typical wax A typical wax (M 10.4)(M 10.4)

Cholesterol Cholesterol (M10.9)(M10.9)

TerpenesTerpenes

Some other biologically active isoprenoid compounds or derivatives.

Steroid Hormones

Separation and analysis of lipidSeparation and analysis of lipid

Lipid extraction requires organic solvent

Adsorption chromatography separates lipids of different polarity

Gas-Liquid Chromatography resolves mixtures of volatile lipid derivatives

Specific hydrolysis(mild acid or alkaline treatment) aids in determination of lipid

structure

Mass spectrometry reveals complete lipid structure

The End The End