BMB 462 Exam 1 Study Guide Lectures 1 9 Lecture 1 Definition of lipids molecules that are not soluble in water Lipids do not contain a structural defining feature like the other biomolecules do Describe the structural features found in common lipids A carboxylic polar head a hydrophobic nonpolar tail saturated or unsaturated typically 12 24 carbon atoms Melting point increases with length of carbon chain and unsaturation Correctly use fatty acid nomenclature Common names these need to be memorized Lauric acid 12 0 Palmitoleic acid 16 1 9 Myristic acid 14 0 Oleic acid 18 1 9 Palmitic acid 16 0 Linoleic acid 18 2 9 12 Stearic acid 18 0 Linoleic acid 18 3 9 12 15 Arachidic acid 20 0 Arachidonic acid 20 4 5 8 11 14 Lignoceric acid 24 0 Shorthand carbon skeletons Chain length double bonds bond position Start counting from the carboxyl group Systematic names have to do with the of Carbons and the of double bonds learn the prefixes i e penta 5 Omega fatty acids start counting from the omega Carbon the carbon in the methyl group on the opposite side of the fatty acid from the carboxyl group The denotes the 1st carbon with a double bond Lecture 2 Predict functions of lipids based on physical and chemical properties Memorize basic structure of triacylglycerol glycerol backbone with 3 fatty acids membrane lipids glycerophospholipids sphingolipids galactolipids sulfolipids sterols the structure of isoprene so you can recognize isoprenoids Identify the bonds in lipids that are cleaved by different lipases know the products Lipases break down lipids for digestion lipid turnover signaling Phospholipase A1 PLA1 cleaves between the fatty acid and Carbon 1 of the glycerol Phospholipase A2 PLA2 cleaves between the fatty acid and Carbon 2 of the glycerol Phospholipase C PLC cleaves between Carbon 3 of glycerol and phosphate Phospholipase D PLD cleaves between the phosphate and the head group Discuss examples of signaling by lipids and the role of NSAIDs in signal disruption Study the bottom figure on page 12 of Lipid Structures Properties and Functions for NSAIDs impact on signaling Lecture 3 Design an experiment separating a mixture of lipids and identify the components Lipids are hydrophobic and cannot dissolve in water which will help separate them from other cellular components i e nucleic acids and proteins which are polar i e in isolation with organic solvents lipids will end up in the organic solvent while all other components will filter into the aqueous solution To separate the various types of lipids once lipids have been isolated use the different polarities in the structures of the lipids to draw them apart via chromatography i e nonpolar lipid structures will be the first to elute while polar lipids remain attached to the silica of the filter Increasing polarity of the wash liquid will elute increasingly polar lipids Mass spectrometry can determine specifically the identities of the lipids Recognize membrane lipids as amphipathic compounds that form lipid bilayers Membrane lipids are only those lipids that have both hydrophobic and hydrophilic areas Describe the functions of membranes How do the components relate to those Membranes act as barriers structural support compartmentalization transport of nutrients waste More proteins in a membrane indicates the membrane does a lot of activity i e transport of molecules E coli has more proteins in the membrane than human myelin sheath b c the bacterial membrane is a barrier to the environment while the sheath is mainly insulation Identify the location orientation and structures of typical lipids proteins in the membrane Membranes are asymmetrical receptor proteins are always oriented outside to receive hormones glycoproteins also commonly located in the outer leaflet for signaling cell cell communication Common membrane lipids are sphingolipids phosphatidylcholine phosphatidylethanolamine Lipoproteins lipid linked proteins remain associated with the membrane so that they can only diffuse around membrane and not through the cell Interpret hydropathy plots The x axis is displayed from the N terminus to the C terminus Nonpolar hydrophobic portions of alpha helices in transmembrane proteins shows up as a positive peak on the plot Beta barrels alternate polar and nonpolar residues so they don t appear on the plots Lecture 4 Describe the fluid mosaic model How is fluidity controlled by fatty acid cholesterol composition The mosaic refers to the variety of components and the asymmetrical aspect of the leaflets Fluidity is due to the fact that the components are not covalently linked so they can move laterally most common or transversely which requires energy so is more rare Cholesterol keeps membranes more stable at a wider range of temperatures by preventing fatty acids from packing in tightly at low temperatures but its rigidity maintains structure at high temperatures Increased unsaturation and shorter fatty acid chains increase fluidity Describe membrane fusion and the processes that rely on it Fusion is the process that binds 2 originally distinct and separate lipid bilayers by merging together their hydrophobic cores It is useful for endocytosis phagocytosis transporting nutrients and waste via vesicles fertilization joining of the egg and sperm Lecture 5 Describe the big picture of membrane transport Small hydrophobic molecules can easily diffuse across the hydrophobic portion of the membrane however larger or charged molecules need help from protein transports Transporters can be very specific to the substrates they let through allowing some molecules across the membrane but blocking others hence the semipermeable nature of membranes Describe compare and contrast the types of diffusion Simple diffusion is the movement of molecules without the aid of energy or transport proteins Facilitated diffusion requires aid of a transporter protein i e ion channels Passive transport does not require energy input active transport does Enzyme catalysis aids in unfavourable movement of molecules i e moving them against their concentration gradient Requires either primary or secondary energy input from ATP Classification of transports Passive Active primary or secondary Channels Carriers Uniporters Cotransporters symport or antiport Be able to describe the GLUT family of transporters as an example of transport Lecture 6 Compare the 3 types of ATP driven transports primary transport P type 4 domains ATP binding causes a conformational change that transfers
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