MCB 450 1st Edition Lecture 8 Outline of Last Lecture I Monosaccharides II Glycosidic bonds III Polysaccharides Outline of Current Lecture I Fatty acids structure nomenclature properties II Lipids components structure properties III Functions of lipids a energy storage b components of cell membranes IV Membrane lipids a phospholipids phosphoglycerides sphingolipids b cholesterol V Lipid bilayers a why they form b bilayer fluidity c lipid mobility and asymmetry Current Lecture Five classes of lipids Fatty acids can have saturated or unsaturated hydrocarbon chains Phospholipids have esterified head groups Sterols polycyclic molecules Major membrane components fatty acids FA C atom most distant is the omega carbon Unsaturated fatty acids Unsaturation means we introduce a double bond 18 1 has one double bond 18 2 has two double bonds Fatty acid nomenclature DO NOT include carbonyl bond when counting double bonds in fatty acids Alkene decen carbon carbon double bound Alkane decan This nomenclature gives some indication to the physical properties of the fatty acid Cis polyunsaturated fats are essential components of our diet Linolenate is the most extreme structure that we will be expected to recognize These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Classes of fatty acid containing lipids Overview slide o Classify lipids based on their function in the cell o Pink blocks show the backbone to which the fatty acids are attached Triacylglycerols Can have different fatty acid chains attached to the same glycerol backbone Neutral and not a great deal of polarity Saponification Linkages can easily be broken Saponification making soap o Treat the triacylglycerol with hydroxyl and it will create detergents Most natural plant and animal fats triacylglycerols Different types of organisms make different triacylglycerols Triacylglycerols are a major energy reserve Are much better at being a major energy reserve than glycogen and glucose stores allow to survive longer o Because they are much more reduced than carbohydrates o Triacylglycerols can be stored more efficiently Carbon containing fuel molecules Octane gasoline Sphingolipids Sphingosine mimics the backbone aka glycerol in a triacylglycerol No ester linkage And longer fatty acid chain does not contain ester linkages So does not break apart when you treat with hydroxyl Originally discovered when they were separated from neural tissue Name of X is the name of the head group o Attachment of different head groups creates different sphingolipids Cholesterol derivatives Cholesterol makes up five families of steroid hormones Hence cholesterol is a very important membrane component Analysis of lipids 1 extraction Try to solubilize the lipids o Will spin out all of the insoluble parts to allow lipids to remain Analysis of lipids 2 separation Then typically the next step is to do some sort of chromatography Detergents are emulsifying agents Example of a detergent molecule emulsifying a drop of grease Lipids self assemble into membranes in an aqueous environment Tail to tail arrangement of two lipid layers they will self assemble into this formation When this formation happens MANY water molecules are freed up Self association of lipids into bilayers Formation is favored even though you are introducing a lot of order to these molecules Bilayer fluidity Go from gel phase to more solid phase to more fluid state If it is below the transition temperature it will undergo the phase change Demonstration of lateral diffusion of lipids Attach fluorescent group to be able to detect where head group are Can conclude that the phospholipids in this bilayer have fused and moved Composition of organellar membranes varies Shows that different cellular membranes have different make ups