CHEMISTRY OF LIPIDS

LIPID CHEMISTRY

Definition Classification

Biological importance

LIPID CHEMISTRY

organic substances relatively insoluble in water but soluble in organic solvents like chloroform,

ether and benzene

Definition LIPIDS

CLASSIFICATION OF LIPIDS

Simple lipids

Complex lipids

Derived lipids

SIMPLE LIPIDSThey are esters of FA with various alcohols

Depending on the type of alcohol they are esterified

with they are subclassified as Neutral fats or Oils

Alcohol is GLYCEROL

Waxes

Alcohol other than

glycerol

NEUTRAL FATS OR OILSEsters of FA with the

alcohol GLYCEROL

Uncharged

WAXESEsters of FA with higher molecular weight monohydric alcohols

EXAMPLES Lanolin Beeswax Carnauba Sperm whale oil Synthetic

spermaceti

These are esters of FA with alcohol containing additional[prosthetic] groups.Subclassified according to the type of prosthetic

group

Phospholipids Glycolipids Lipoproteins

COMPLEX LIPIDS

FA + ALCOHOL + PHOSPHORIC ACID

PHOSPHOLIPIDS

They frequently have

nitrogen containing bases

Phospholipids may be classified on the basis of the type of alcohol present

PHOSPHOLIPIDS

A. Glycerophospholipids

B. Sphingophospholipids

ALCOHOL IS GLYCEROL ALCOHOL IS SPHINGOSINEPhosphatidylcholine Phosphatidyl

ethanolaminePhosphatidyl serinePhosphatidyl

inositolPlasmalogensCardiolipins

Sphingomyelins

SPHINGOPHOSPHOLIPID

FA + ALCOHOL[SPINGOSINE] + CARBOHYDRATE WITH NITROGEN BASE

They do not contain any phosphate group

Examples Cerebrosides Gangliosides

GLYCOLIPIDS

GLYCOLIPIDS

Chylomicrons Very low density lipoprotein (VLDL)Low density lipoprotein (LDL)High density lipoprotein (HDL)

LIPOPROTEINS

Lipid with prosthetic group PROTEIN

Derived from lipids (simple or complex) or precursors of lipids

Examples Fatty acids Steroids Cholest

erol Vitamin A and D

DERIVED LIPIDS

FUNCTIONS OF LIPIDS

Storage form of energy

Structural component of cell membran

e

Precursor of many steroid

hormones, vitamin

D

Act as thermal insulator

Protection of internal

organs

FUNCTIONS OF LIPIDS

Bile acids help in

absorption of fat soluble

vitamins

Lipoproteins serve

to transport

lipids

Fats serve as

surfactants by

reducing surface tension

Improve food taste

and medicatio

n palatabilit

y

Act as electric

insulators in neurons