Lipids are naturally occurring organic compounds that are soluble in organic solvents but insoluble in water. They include fats, oils, waxes, phospholipids, and steroids. Lipids are classified as simple lipids like triglycerides and waxes, or compound lipids like phospholipids. The main roles of lipids include serving as energy stores, components of cell membranes, and intermediaries in signaling pathways. Essential lipids like omega-3 and omega-6 fatty acids must be obtained through diet as the body cannot produce them. Lipids are important for many biological functions including energy storage, cell membrane structure, hormone synthesis, and brain and vision health.

1. Chapter # 21
XII FDC Prepared by: Sidra Javed

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3. Lipids
 Greek, Lipos means Fat
 Naturally occurring organic
compounds
 Soluble in organic solvents but
insoluble in water
 Includes Fats & oils, Waxes,
Phospholipids, Steroids etc.
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4. Main Composition
 Mainly contains C, H & O atoms.
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5. Constituents of:
 Cell membranes of animal & plant cells
 Food storage molecules
 Intermediaries in signaling pathways
 Vitamins A, D, E and K
 Cholestrol
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6. Hydrophobic in nature!
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7. Fats & Oils - Triglycerides
 Two kinds of molecules
 Glycerol
 Fatty acids
 Dehydration synthesis
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9. Classification
Lipids
Simple
Lipids
Triglycerides
Waxes
Compound
lipids
Phospholipids
(Phosphatides)
Plasmalogen
Lipositol
Sphingomyelin
Derived
Lipids
Fatty Acids
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10. Simple Lipids
 Ester of fatty acids with glycerol
 Triglycerides, neutral fats
 Adipose tissues, butterfat, fish oils, olive oil & Corn oil
 Waxes
 Beeswax, head oil of sperm whale, carnauba oil and
lanolin of industrial and medicinal importance
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11. Simple Lipids - Triglycerides
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12. Simple Lipids - Triglycerides
ButterFatPrepared by: Sidra Javed

13. Simple Lipids - Triglycerides
Fish Oil
Olive Oil
Corn Oil
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14. Simple Lipids - Waxes
Beeswax
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15. Simple Lipids - Waxes
Head Oil of Sperm Whale
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16. Simple Lipids - Waxes
Carnauba Wax (Brazilian Palm)
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17. Simple Lipids - Waxes
Lanolin Oil (Wool Wax)
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18. Compound Lipids
 Radicals in addition to fatty acids & alcohols
 Phospholipids (Phophatides) – Animal tissues, Plasma
Membrane of Animal & Plant Cells
 Plasmalogen – Brain, Heart & Muscles
 Lipositol – Brain, Heart, Kidneys & Plant tissues
together with phytic acid
 Phosphatidyl inositol; rapid synthesis & degradation in brain,
cell transport processes
 Sphingomyelin – Nervous tissues, Brain & Red Blood
cells. Source of Phosphoric acid in body tissue.
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19. Compound Lipids - Phospholipids
Plasma MembranePrepared by: Sidra Javed

20. Compound Lipids - Plasmalogen
Brain
Heart
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21. Compound Lipids - Lipositol
Brain Heart
Kidneys
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22. Compound Lipids - Lipositol
Plant tissue
(Microscopic View)
Phosphatidyl
Inositol
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23. Compound Lipids – Sphingomyelin
Brain
Nervous
tissue RBCs
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24. Derived Lipids
 Hydrolytic product of
compound lipids
 Fatty Acids
 Plant & animal foods
 Complex forms with other
substances
 Obtained from hydrolysis of fats
 Straight chain hydrocarbon
derivatives
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25. Structure of Lipids
Tail of Fatty acid molecule – Hydrophobic End
Long hydrocarbon chain
Head of fatty acid molecule – Hydrophilic end
Carboxyl GroupPrepared by: Sidra Javed

26. Interaction with Water
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28. Saturated & Unsaturated Lipids
 Number of hydrogen attached to the hydrocarbon tails
of fatty acids as compared to the number of double
bonds between carbon atoms in the tail.
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29. Saturated Fats
 Animal fats
 Straight Hydrocarbon chains are closely packed
together
 Solids at room temperature
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30. Unsaturated Fats
 Oils – Mostly from Plant sources
 Double bonds in hydrocarbon chains causes Bends or
Kinks in the shape of molecule
 Liquid at room temperature
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31. Physical Properties of Lipids
 May be either liquid or non crystalline solids at room
temperature
 Colorless, odorless and tasteless in their pure state
 Color of fat is due to other substances
 Yellow color of butter is due to Keratin
 Lighter than water
 Insoluble in water
 Readily soluble in organic solvents
 Form emulsions when agitated with water in the
presence of soap or other emulsifier
 Poor conductor of heat and electricity – efficient
insulator for animal body
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32. Chemical Properties of Lipids
 Hydrolysis Of Fats And Oils
 Reverse of Esterification
 Carboxylic acids (Fatty Acids) and Alcohols are formed
 Catalyst – acid or enzyme (Lipase)
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33. Chemical Properties of Lipids
 Saponification Reaction
 Hydrolysis in basic medium
 Glycerol and Soap i.e. Na or K salts of Fatty Acids are
produced
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34. Chemical Properties of Lipids
 Hardening Of Oils
 Unsaturated triglycerides (Oils) are liquid at room temp.
 Hydrogenation – H2 is passed in presence of Metal
catalyst
 Saturated Triglycerides (Fats) are produced which are
semisolids
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35. Nutritional & Biological Importance
 As a Storage form for metabolic energy (triglycerides)
 As components of membranes
 As messengers (prostaglandins, Steroid hormones)
 Lipids provide 9 calories per gram energy as compared
to Carbohydrate or Protein with 4 calories per gram.
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36. Essential Lipids
 Polyunsaturated Fats
 Omega-6 and Omega-3 Fats
 Essential part of diet
 Good for health
 Body cannot produced these lipids
 Hormone synthesis, Cell membrane structure and
healthy brain & vision.
 Lower body cholesterol levels
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37. Omega-6
 Found in Vegetable oils & Nuts
 Regulates brain functioniing
 Regulates growth and development
 Maintains healthy bones and reproductive system
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38. Omega-3
 Fatty fish (salmon, cod etc), Soybeans, Flaxseed,
Walnuts, Green Vegetables
 Controls blood clotting
 Enhances brain and joint functions
 Reduces risks of Cancer, heart diseases and Diabetes
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39. Non-Essential Lipids
 Monounsaturated Fats
 Synthesized in body
 Not essential in diet
 Reduce risk for heart Diseases Olive Oil
Peanuts Avocadoes
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40. Bad Fats
 Raise Bad cholesterol levels in blood
 Should be avoided in diet
 Saturated Fats
 Fatty meats , Butter & cheese, Palm & Coconut Oil
 Trans Fats
 Partially Hydrogenated oils
 Processed and fried foods
 Cholesterol
 Fatty animal foods
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41. Other Functions of Lipids
 Tissue reconstruction
 Nervous system Organization
 Increases and assures a normal function of the skin
 Antibodies formation
 Good function of endocrine glands (Thyroid)
 Water metabolism
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