Lecture 17Outline of Last Lecture I. Carbohydrate NamesII. MonosaccharidesA. Fischer ProjectionsB. StereoisomersC. D and L SugarsIII. Cyclic MonosaccharidesA. Alpha and Beta AnomersIV. DisaccharidesA. Glycosidic BondB. StarchC. Glycogen Outline of Current Lecture I. LipidsA. Functions of LipidsII. Fatty AcidsA. Characteristics of Fatty AcidsB. Unsaturated LipidsIII. Essential Fatty AcidsIV. TriacylglycerolCurrent LectureThe next chapter and lectures will focus on lipids. Lipids can be either entirely hydrophobic or amphiphilic. Most are insoluble in water. They are soluble with each other always. Lipids can be highly compacted together. The common function of lipids is to act as a storage center. They are also a part of biological membranes. Cholesterol derivatives act as hormones. Lipids are named based upon the ancient process of soap-making. Lipids that can be made into soaps are called saponifiable. Those in this group include the following: glycolipids, sphigolipids, phosphoacylglycerols, triacylglycerols, and fatty acids. Let’s start by looking at fatty acids.Fatty acids are characterized by their long carboxylic acid chains. The chains contain between 12 and 20carbon atoms that are added on in pairs of two. Fatty acids are involved in hydrophobic interactions, due to their functional groups not participating in hydrogen bonding. Fatty acids also often contain a double bond, creating unsaturated fatty acids. Those with more than one double bond are called polyunsaturated fatty acids.The double bonds are usually in the cis form, causing a kink in the chain. This prevents the fatty acids from packing as tightly together. Fatty acids have polar head groups as well.Different fatty acids can be in the same lipid. Longer chained fatty acids have more carbons that can interact more. The chain length also influences the lipid’s melting point. The shorter chain is, the lower the melting point. The melting point relates to how much heat energy has to be put in. How unsaturated a lipid is also plays a role in the melting point. Unsaturated lipids are liquid at room temperature. The more double BCHM 307 1nd Editionbonds there are, the more kinks in the lipid, and therefore the lower the melting point. Certain fatty acids are essential, just as there are essential amino acids. They are often referred to as Omega-3’s. These include Linolenic acid, EPA, and DHA.Next up are triacylglycerols. They contain 3 fatty acid chains. These are linked to a glycerol molecules through an ester
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