Lipids

These slides explains about lipids.

1. LIPIDS

2. ABHAY GUPTA-AAA1327 DINESH BHATI-AAA1363

3. Topics covered What are lipids(Fats) ? Functions Structure Types Associated diseases AIM - Just to revise what mam has taught.

4. INTRODUCTION Lipids are compounds of biological origin that dissolve in nonpolar solvents, such as chloroform and diethyl ether. The name lipid comes from the Greek word lipos , for fat.

5. DEFINITION Lipids can best be defined as biomolecules which are soluble to a great extent in nonpolar solvents.

6. Lipids can be categorized as hydrolyzable or nonhydrolyzable Hydrolyzable lipids can be cleaved into smaller molecules by hydrolysis with water. Most hydrolyzable lipids contain an ester unit. We will examine three subgroups: waxes, triacylglycerols , and phospholipids . Nonhydrolyzable lipids cannot be cleaved into smaller units by aqueous hydrolysis. Nonhydrolyzable lipids tend to be more varied in structure. We will examine four different types: fat-soluble vitamins, eicosanoids, terpenes , and steroids .

7. WAXES Waxes are the simplest hydrolyzable lipids. Waxes are esters (RCOOR') formed from a high molecular weight alcohol (R'OH) and a fatty acid (RCOOH).

8. The structure of this compound shows how small the ester group is compared to the long hydrocarbon chains.

9. Wax is a generic term that encompasses materials that have some specific properties such as: Solid at 20  C , varying from soft / plastic to brittle / hard A melting point > 40  C without decomposing A relatively low viscosity slightly above the melting point Transparency to opaque, but not glass-like Buffable under slight pressure

10. TRIACYLGLYCEROLS Triacylglycerols , or triglycerides, are triesters that produce glycerol and three molecules of fatty acid upon hydrolysis. Simple triacylglycerols are composed of three identical fatty acid side chains, whereas mixed triacylglycerols have two or three different fatty acids.

11. The characteristics of fatty acids All fatty acid chains are unbranched , but they may be saturated or unsaturated. Naturally occurring fatty acids have an even number of carbon atoms. Double bonds in naturally occurring fatty acids generally have the Z configuration. The melting point of a fatty acid depends on the degree of unsaturation.

12. Fats and oils are triacylglycerols ; that is, they are triesters of glycerol and these fatty acids. Fats have higher melting points, making them solids at room temperature. Oils have lower melting points, making them liquids at room temperature.

13. VIDEO Now have a look on the video which clearly depicts the difference between satuarated vs unsaturated fatty acids

14. Soap and detergent

15. PHOSPOLIPIDS

16. Phospholipids are hydrolyzable lipids that contain a phosphorus atom. There are two common types of phospholipids: phosphoacylglycerols and sphingomyelins .

17. Phosphoacylglycerols • When R'' = CH2CH2NH3+, the compound is called a phosphatidylethanolamine or cephalin . • When R'' = CH2CH2N(CH3)3+, the compound is called a phosphatidylcholine , or lecithin.

18. VIDEO Now have a look on the video which clearly depicts the 3D structure of phospholipids.

19. Sphingomyelins Other notable features of a sphingomyelin include: = • A phosphodiester at C1. = • An amide formed with a fatty acid at C2 .

20. FAT-SOLUBLE VITAMINS

21. EICOSANOIDS

22. The word eicosanoid is derived from the Greek word eikosi , meaning 20.

23. TERPENES

24. Terpenes are lipids composed of repeating five-carbon units called isoprene units. An iso - prene unit has five carbons: four in a row, with a one-carbon branch on a middle carbon.

25. An isoprene unit may be composed of C– C σ bonds only, or there may be π bonds at any position. Isoprene units are always connected by one or more carbon–carbon bonds. Each carbon atom is part of one isoprene unit only. Every isoprene unit has five carbon atoms. Heteroatoms may be present but their presence is ignored in locating isoprene units.

26. STEROIDS

27. Steroids are important “biological regulators” that nearly always show dramatic physiological effects when they are administered to living organisms. Among these important compounds are male and female sex hormones, adrenocortical hormones, D vitamins, the bile acids, and certain cardiac poisons. Steroids are derivatives of the following perhydrocyclopentanophenanthrene ring system:

28. Thank You