The membrane lipids

all about the membrane lipids and components

1. MEMBRANE LIPIDS

2. INTRO Membranes contain a wide diversity of lipids All of which are amphipathic ; that is, they contain both hydrophilic and hydrophobic regions . There are three main types of membrane lipids : phosphoglycerides , sphingolipids , and cholesterol.

3. Phosphoglycerides Called as phospholipids Has phosphate group attached to glycerol backbone and other two carbon atoms linked to fatty acid chains Triglycerides have three fatty acids, but membrane glycerides have two fatty acid chains The third carbon attached to phosphate group forms – PHOSPHATIDIC ACID

4. Further the phosphate group attached to Choline ( phosphotidylcholine ) Ethanolamine ( phosphotidylethanolamine ) Serine ( phosphotidylserine ) Inositol ( phosphotidylinositol ) This forms the water soluble domain – HEAD GROUP At physiological pH – PS and PI – negative charge - PE and PC – positive charge

5. Fatty acid chains – 16-22 carbons Contains one saturated and one unsaturated fattyacyl chain

6. Phospholipids

7. Sphingolipids Derivative of sphingosine (amino alcohol) Spingosine linked to fatty acid by amino group – CERAMIDE Additional groups are esterified to terminal alcohol of sphingosine moiety – if phosphorylcholine – SPHINGOMYELIN if carbohydrate – glycolipid – simple sugar – CEREBROSIDE cluster of sugars – GANGLIOSIDES NERVOUS SYSTEM – RICH IN GLYCOLIPID - GALACTOCEREBROSIDE

8. Sphingolipids

9. Cholestrol Abundant in animal cells Oriented with their small hydrophilic OH group toward the membrane surface and remainder of molecule in lipid bilayer Hydrophobic rings are flat and rigid and interfere with movement of fatty acid tails

10. Cholesterol

11. Nature and importance of bilayer Lipid composition determines the physical state of membrane and influence activity of membrane proteins Facilitates fusion or budding or membrane Has the ability to self assemble – eg . Liposomes – wall of fluid filled spherical vesicles