Phospholipid & Membrane Transport Kit Student Handout 1 Key

.where molecules become real TMPhospholipid & Membrane Transport Kit Student Handout 1 KeyPhospholipid Activity 1 ContinuedBig IdeaIn the biological sciences, a dehydration synthesis (condensation reaction) is typically definedas a chemical reaction that involves the loss of water from the reacting molecules. This reactionis used in the formation of carbohydrates, proteins, triglycerides and phospholipids.Introduction to LipidsBiomolecules are molecules unique to living systems and include carbohydrates, proteins,nucleic acids and lipids. Lipids are a diverse group of organic compounds primarily composedof carbon, hydrogen and oxygen. Fatty acids, triglycerides, phospholipids, fat-soluble vitaminsand steroids are a few examples of molecules classified as lipids.The main biological functions of the many varied types of lipids include: energy storage protection insulation regulation of physiological processesSome lipids serve as the structural components of cell membranes.Model PartsCPK Color SchemeOxygen(red)Center for BioMolecular w)Student Handout 1 KeyPage 1Hydrogen(white)Carbon(grey)3D Molecular Designs3dmoleculardesigns.com

.where molecules become real TMPhospholipid & Membrane Transport Field Test Kit Phospholipid Activity 1Hydrophobic and Hydrophilic PropertiesUnderstanding the concepts of hydrophobic andhydrophilic are key to understanding membranestructure. You can divide the words into their two partsto find clues to their meaning. “Hydro” means waterand “phobic” means fear of. Hydrophobic regions ofmolecules don’t interact with water molecules.Chemical PropertiesHydrophobic (non-polar)(gray & yellow)Hydrophilic (polar)(white & red)1. Separate the word hydrophilic into two parts andrecord what each of these parts means.waterlovingHydro means andphilic means .2. What characteristics would a hydrophilic molecule exhibit?Hydrophilic molecules — or portions of molecules — interact with water molecules.You may also see hydrophobic molecules called non-polar and hydrophilic molecules called polar.What’s a Lipid?Fatty acids are linear chains of carbon and hydrogen atoms with an organic acid group(-COOH) at one end. Examine the model of a fatty acid pictured in the box below.1. Review the image of the phospholipid tail, one of the foam model pieces in the kit.a. Label the carbon, oxygen and hydrogen atoms, and note the hydrophobic and hydrophilicregions of the molecule.b. Draw the molecular formula for this fatty acid.HydrophilicOxygen atomsCarbon atomsCenter for BioMolecular Modelingcbm.msoe.eduHydrogen atomHydrophobicStudent Handout 1 KeyPage 2OHC OCH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH33D Molecular Designs3dmoleculardesigns.com

.where molecules become real TMPhospholipid & Membrane Transport Field Test Kit Phospholipid Activity 1 Continued2. Compare the proportion of carbon atoms to oxygen atoms of a common fatty acid(stearic acid) with a common carbohydrate (glucose) in the table below.SubstanceFormula# of C atoms# of O atomsRatio of C:OStearic acidCH3(CH2)16CO2H1829:1C6H12O6661:1Glucose3. What do you notice about the amount of oxygen in a fatty acid compared to oxygen in acarbohydrate?There is less oxygen to carbon in a fatty acid than in a carbohydrate.Triglycerides are neutral fats. Some triglycerides are considered fats and others oils. Whena triglyceride is a solid at room temperature it is a fat. When a triglyceride is a liquid at roomtemperature it is an oil. The two building blocks that compose triglycerides are fatty acids andglycerol.4. Label the glycerol and fatty acids in the diagram below.GlycerolFatty AcidsCenter for BioMolecular Modelingcbm.msoe.eduStudent Handout 1 KeyPage 33D Molecular Designs3dmoleculardesigns.com

.where molecules become real TMPhospholipid & Membrane Transport Field Test Kit Phospholipid Activity 1 ContinuedForming TriglycerideIn this activity you will model a dehydration synthesis reaction in the formation of a triglycerideand determine the resulting products.1. Begin with glycerol and three of the straight-chain fatty acids as the reactants in thissimulation. A fatty acid is said to be saturated if the carbons comprising the tail are all singlybonded to each other.2. Remove one of the hydrogen(H) atoms from the glycerol.3. Remove the hydroxyl group (OH)from one of the fatty acids.4. Combine the H and the OH.5. Join the fatty acid to the glycerol.Center for BioMolecular Modelingcbm.msoe.edu6. Repeat this process with the tworemaining fatty acids.Student Handout 1 KeyPage 43D Molecular Designs3dmoleculardesigns.com

.where molecules become real TMPhospholipid & Membrane Transport Field Test Kit Phospholipid Activity 1 Continueda. How many water molecules were formed in thisreaction?3b. What are the final products of this dehydrationsynthesis?3 water molecules and 1 triglyceridec. Predict whether you think this resultingtriglyceride would most likely be a fat or an oil?Explain your reasoning.The triglyceride will most likely be a fat due tothe saturated fatty acid tails. These tails willpack together tightly, forming a solid material.7. Substitute the third fatty acid tail with the two-part fatty acid tail. The post and holeconnection in the two-part tail symbolizes a double bond between the carbons. Whenone or more double bonds are present between the carbons in the tail of the fatty acid, themolecule is unsaturated.DoubleBondCenter for BioMolecular Modelingcbm.msoe.eduStudent Handout 1 KeyPage 53D Molecular Designs3dmoleculardesigns.com

.where molecules become real TMPhospholipid & Membrane Transport Field Test Kit Phospholipid Activity 1 ContinuedThe double bond in an unsaturated fatty acid may form one of two possible configurations: transor cis. You may model the trans configuration by attaching the second piece of the tail to thefirst to produce a straighter chain. The cis configuration may be modeled by producing a kinkedconfiguration. Most naturally-occurring unsaturated fats are in the cis configuration.If the hydrogens associated with the double bonded carbons are on the same side, the fatty acidis called cis. If the hydrogens associated with the double bonded carbons are on opposite sides,the fatty acid is called trans. (See illustrations below.)DoubleBondsCisTransd. Which configuration produces the bigger kink in the structure of the hydrocarbon chain ofthe triglyceride?cise. Explain how the cis or trans configurations might contribute to the triglyceride being an oilor a fat?An oil would more likely be formed due to the cis kink in the fatty acid tail, which wouldpromote more fluidity.Center for BioMolecular Modelingcbm.msoe.eduStudent Handout 1 KeyPage 63D Molecular Designs3dmoleculardesigns.com

.where molecules become real TMPhospholipid & Membrane Transport Field Test Kit Phospholipid Activity 1 Continuedf.Is the fatty acid in the diagram above in the cis or trans configuration? Explain.The molecule is in the cis configuration because the hydrogens are located on thesame side of the double bonded carbons.Hydrogenation occurs when hydrogen atoms are added to an unsaturatured fatty acid tail,causing double bonds between atoms to become single bonds.Full hydrogenation occurs when all double bonds convert to single bonds resulting in asaturated fatty acid.Partial hydrogenation occurs when some of the double bonds are replaced with single ones.Trans fat may be created in partial hydrogenation.Hydrogen attacks a doublebond of a cis, causing eitherpartial hydrogenation orcomplete hydrogenation.lnrtia tioPa enarogydA hydrogen atom moves tothe other side of the doublebond, creating a transisomer.HHy Comdro plge etenationCenter for BioMolecular Modelingcbm.msoe.eduStudent Handout 1 KeyPage 7A hydrogen atom adds toeach side of the doublebond, saturating thehydrocarbon chain.3D Molecular Designs3dmoleculardesigns.com

.where molecules become real TMPhospholipid & Membrane Transport Field Test Kit Phospholipid Activity 1 ContinuedIntroduction to Plasma MembranesThe plasma membrane is the structural boundary that separatesthe cell from its surroundings and controls what substances moveinto and out of the cell it surrounds. As only some substancesare allowed to cross the membrane, the plasma membranedemonstrates the property of selective permeability.The plasma membrane is also called a cell membrane.Water molecules (shown in circle)can pass in and out of a cell througha plasma membrane, but not easily.A protein embedded in the plasmamembrane, aquaporin, facilitatespassage of water molecules in andout of the cell.In the plasma membrane thehydrophobic tails come togetherwhile the hydrophilic heads of eachlayer orient themselves toward thewatery environments inside andoutside of the cell.In particular, the plasma membrane of mammalian red bloodcells (erythrocytes) has been the focus of cell membrane studybecause these cells do not contain nuclei or internal membranes.They represent a source from which a pure plasma membranemay be easily isolated for analysis. In 1925, Dutch scientist EvertGorter and his research assistant F. Grendel extracted lipidsfrom the membranes of a known number of red blood cells whichcorresponded to a known surface area of plasma membrane. Thesurface area occupied by a monolayer of the extracted lipid andthe air/water interface was then determined. The results of theirexperiment showed that the surface area of the lipid monolayerwas twice that occupied by the erythrocyte plasma membrane,leading to the conclusion that the plasma membrane consists oflipid bilayers.The most abundant lipids in most membranesare phospholipids. The ability of phospholipidsto spontaneously form membranes is inherent totheir amphipathic (containing both hydrophilicand hydrophobic regions) nature. The “head” ofa phospholipid is composed of the negativelycharged phosphate group and may contain otherpolar groups. The tail of a phospholipid usuallyconsists of long fatty acid hydrocarbon chains.Plasma membranes primarilyconsist of phospholipids.Note the hydrophobic andhydrophilic regions of the lipid.Models shown are from the 3D Molecular Designs Molecules of Life Collection . The Molecules of Life canbe borrowed from the MSOE Lending Library cbm.msoe.edu/teachRes/library/ml.html or purchased from3D Molecular Designs s-of-Life-Collection.htm.Due to the relatively higher cost of the collection, we suggest you borrow it. As an alternative, you may wantto purchase a set of the monomers and the placemat. The cell membrane can also be purchased separately.Center for BioMolecular Modelingcbm.msoe.eduStudent Handout 1 KeyPage 83D Molecular Designs3dmoleculardesigns.com

.where molecules become real TMPhospholipid & Membrane Transport Field Test Kit Phospholipid Activity 1 ContinuedFocus on PhospholipidsThe building blocks of a phospholipid include two fatty acid tails, the glycerol backbone anda phosphate head. In this next activity you will model a dehydration synthesis reaction in theformation of a phospholipid.1. Begin with one of the straight-chain fatty acids (saturated), the kinked-chain fatty acid(unsaturated), glycerol and one of the phospholipid heads as the reactants in this simulation.GlycerolStraight-ChainSaturated Fatty Acid(Trans Configuration)Phosphate Head(Phosphotidlycholine)Kinked-ChainUnsaturated Fatty Acid(Cis Configuration)2. Remove one of the hydrogen (H)atoms from the glycerol.3. Remove the hydroxyl group (OH)from one of the straight fatty acids.4. Combine the H and the OH.Center for BioMolecular Modelingcbm.msoe.eduStudent Handout 1 KeyPage 93D Molecular Designs3dmoleculardesigns.com