Definition Classification Functions Definition Organic substances relatively insoluble

Definition Classification Functions

Definition Organic substances relatively insoluble in water but soluble in organic solvents like chloroform, ether and benzene

Simple lipid Complex lipid Derived lipids

They are esters of FA with various alcohols the type of alcohols these are subclassified as Neutral fats or oils Waxes Alcohol is GLYCEROL Alcohol is other than glycerol

Esters of FA with alcohol GLYCEROL Uncharged

Esters of FA with higher molecular weight monohydric alcohols EXAMPLES ü Lanolin ü Beeswax ü Whale sperm oil

Classification of FATTY ACIDS According to presence or absence of double bonds they are classified into: • Saturated fatty acids • Unsaturated fatty acids 1 -Saturated Fatty Acids � no double bonds with 2 -24 or more carbons. � solid at RT except if they are short chained. � may be even or odd numbered. � molecular formula, Cn. H 2 n+1 COOH. �Ex: palmitic(16 C) CH 3 -(CH 2)14 -COOH stearic (18 C ) CH 3 -(CH 2)16 -COOH

2 -Unsaturated Fatty Acids contain double bond - TYPES: A. monounsaturated they contain one double bond. (Cn. H 2 n-1 COOH) Ex. Palmitoleic acid B. polyunsaturated they contain more the one double bond (Cn. H 2 n-1 COOH). Ex. Linolenic acid -

These are esters of FA with alcohol containing additional attached groups. Subclassified according to the type of attached group Phospholipids Glycolipids Lipoproteins

FA + ALCOHOL + PHOSPHORIC ACID They frequently have nitrogen containing bases

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

A. Glycerophospholipids ü Phosphatidylcholine ü Phosphatidyl ethanolamine ü Phosphatidyl serine ü Phosphatidyl inositol ü Cardiolipins B. Spingophospholipids ü Spingomyelins

FA + ALCOHOL[SPINGOSINE] +CARBOHYDRATE WITH NITROGEN BASE q They do not contain phosphate group Example üCerebrosides üGangliosides

Lipid with prosthetic group PROTEIN üChylomicrons üVery low density lipoprotein (VLDL) üLow density lipoprotein (LDL) üHigh density lipoprotein (HDL)

Example Fatty acids Steroids Vitamin A Cholesterol and D

STEROIDS • • o o o Based on a fused ring structure - No ester linkages - Includes HORMONES (testosterone, progesterone, estrogen) Cholesterol Common membrane lipid Almost exclusive to animal cells Very hydrophobic but amphiphilic Hydrophilic group is the –OH Serves as the starting point for synthesis of steroid hormones

Cholesterol Structure

Storage form of energy Structural component of cell membrane. Precursor of many steroid hormones, vitamin D Act as thermal insulator Protection of internal organs

Helps in absorption of fat soluble vitamins Lipoproteins transporting lipids Acts as electric insulators in neurons.

Long Define lipids, classify lipids with Essay (10 suitable examples and mention marks) their functions. Short Essay (5 marks) Phospholipids Glycolipids