Chapter 13 Section 13.4-13.8

1. Chapter 13 Section 13.4-13.8 Savannah, Ashley, Erika

2. Section 13.4 What are the Structures of Complex Lipids? Complex Lipids: • Complex lipids are important because they constitute the main components of membranes. • Complex lipids can be classified into two groups. Phospholipids: • Contain an alcohol, two fatty acids, and a phosophate group • There are two types: • Glycerophospholipids have glycerol as the alcohol • Sphingolipids have sphingosine as the alcohol

3. Section 13.4 (cont.) Glycolipids: • These are complex lipids that contains carbohydrates

4. Section 13.5 What Role Do Lipids Play in the Structure of Membranes? Structure of Complex Lipids • Complex lipids form the membranes around body cells and around small structures inside the cells. • These membranes are made up of lipid bilayers • Unsaturated fatty acids are important components because they prevent the tight packing of the hydrophobic chains in the lipid bilayers

5. Section 13.5 (cont.) • The fluid mosaic model of membranes allows the passage of nonpolar compounds by diffusion. These compounds are soluble in the lipids membranes.

6. Section 13.6 • What are Glycerophospholipids? • Similar structure to fats • Membrane components throughout the body • Alcohol is glycerol • 2 out of 3 groups are esterified by fatty acids • The third group is esterfied by a phosphate group, which is also esterfied to another alcohol • If the other alcohol is choline, a quarternary ammonium compound, the glycerophospholipids are called phosphatidylcholines (lecithin)

7. Section 13.6 (cont.) • May be long-chain carboxlyic acids, with or without double bonds • In glycerophospholipids, lecithins, caphalins, and phosphatidylinositols, the fatty acid on carbon 2 of glycerol is ALWAYS unsaturated

8. Section 13.6 (cont.) • Lecitin • Stearicacid on one end and linoleic acid in the middle • Others contain other fatty acids, but the one on the end is always saturated and the one in the middle is always unsaturated • Major compo nent of egg yolk

9. Section 13.6 (cont.) • Includes both polar and nonpolar portions all within one molecule • Excellent emulsifier • Used in mayonnaise • Negitively charged phosphate group • Positively charged quaternary nitrogen from the choline • Hydrophilic head, rest is hydrophobic

10. Section 13.6 (cont.) • Cephalins • Similar to lecithins in every way except for having other alcohols such as ethanolamine or serine instead of choline • Phosphatidylinositols (PI) • Alcohol insolitol is bonded to the rest of the molecule by a phosphate ester bond • Have higher forms such as phosphatidylinositol4,5-bisphosphates (PIP2) • Serve as signaling molecules in chemical communication

11. Section 13.7 • What are Sphingolipids ? • The different complex lipids found in the nerve axons coating, Myelin • Not randomly distributed in membranes • Example • Viral membranes appear on the inside

12. Section 13.7 (cont.) • Alcohol portion is Sphingosine • Long –chain fatty acid • Connected by –NH₂ by amide bond • -OH group is on the other end

13. Setions 13.7 (cont.) • Ceramide • Fatty acid combined with sphingosine • Colored part • Complex lipids – many different fatty acids

14. Section 13.7 (cont.) • Sphingomyelins • Most important lipids in the myelin sheaths • Johann Thudichum • Discovered in 1874 • Named them after Greek mythology monster - Sphink

15. Section 13.8 • What Are Glycolipids? • Complex lipids • Made up of Carbohydrates and ceramides

16. Section 13.8 (cont.) • Cerebrosides is made up of mono- or oligosaccha of ceramide • 18-carbon or 24- carbon chains • Primarily in the brain • Nerve synapses • Glangliosides are made up of more complex carbohydrate structure