1. 13.4-13.8 COMPLEX LIPIDS

2. WHAT ARE COMPLEX LIPIDS Help to create the main components of membranes AKA compound lipids Complex lipids can be classified into 2 groups Phospholipids Gylcolipids

3. WHAT ARE PHOSPHOLIPIDS?? Contain: At least 1 fatty acid Phosphate group And sometimes a nitrogen containing a phosphate ester 2 types Glycerophopholipids Sphingolipids Most are made in the liver and then put into the bloodstream

4. GLYCEROPHOSPHOLIPIDS Glycerophospholipids are also called phosphoglycerides Structure is very similar to fats Membrane components of cells throughout the body The alcohol is glycerol Fatty acid on carbon 2 of glycerol is always unsaturated

5. LECITHIN Lecithin- common name for phosphatidylcholines Typical lecithin molecules have stearic acid on one end and linoleic acid in the middle Major component of egg yolk Has polar and nonpolar portions in each molecule Excellent emulsifier = used in mayonnaise

6. SPHINGOLIPIDS Different type of complex lipid Fatty acid + sphingosine = ceramide portion of the molecule Ceramide part of complex lipids may contain different fatty acids Sphingomyelins- most important lipids in myelin sheaths of nerve cell Associated with diseases like multiple sclerosis Not randomly distributed in membranes

7. Johann Thudichum- discovered Sphingolipids in 1874 Named them after the Sphinx

8. GLYCOLIPIDS Complex lipids that contain carbohydrates and ceramides One group- Cerebrosides Made of ceramide mono- or oligosaccharides Fatty acid of the ceramide may contain either 18 or 24 carbon chains Mainly occur in the brain & nerve synapses Other groups- Gangliosides Contain more complex carbohydrate structure

9. Contain mono- or oligosaccharides Mostly in the brain Make up about 70% of the brain dry weight

10. WHAT ARE MEMBRANES? Made up of lipid bilayer Lipid bilayer- 2-layered structure of complex lipids set tail-tail Hydrophobic- tails point towards each other Hydrophilic- tails point towards away from each other Which makes them closer to the water

11. Most lipid molecules in the bilayer contain at least one unsaturated fatty acid Unsaturated fatty acids prevent tight packing of hydrophobic chains in lipid bilayer Liquid like characteristics because the unsaturated fatty acids prevent tight packing in the lipid bilayer

12. Important component is Cholesterol Similar structure to other membranes

14. CON’T Lipid part of membrane serves as a barrier against movement of ions The fluid mosaic model of membranes allows non- polar compounds to pass by diffusion Polar compounds are transported by channels through protein regions

15. CON’T Contains a negatively charged phosphate groups and positively charged nitrogen Charged parts provide a strong hydrophilic head Rest of the molecule of hydrophobic

16. WHAT DO LIPIDS DO FOR MEMBRANES?? Complex lipids form membranes around organelles Small structures inside the cells Provide selective transportation for nutrients and wastes in and out of cells Important component- unsaturated fatty acids especially in lipid bilayer Separate cells from external structure