Lipids Slides PDF

Lipids Fatty Acid Names Are Based on Their Parent Hydrocarbons Structures of Two Fatty Acids Some Naturally Occurring Fatty Acids in Animals Lipids could be categorized as Storage or Membrane Lipids Triacylglycerol – neutral storage lipid -Glycerol backbone -3 fatty acyl chains -Ester...

Lipids Fatty Acid Names Are Based on Their Parent Hydrocarbons Structures of Two Fatty Acids Some Naturally Occurring Fatty Acids in Animals Lipids could be categorized as Storage or Membrane Lipids Triacylglycerol – neutral storage lipid -Glycerol backbone -3 fatty acyl chains -Ester bonds Simple versus mixed triacylglycerols (triglycerides) Identical fatty acids Mixed fatty acids Fatty acid composition of three food fats Saponification – hydrolysis of ester bonds of TAGs by NaOH or KOH Waxes – esters of fatty acids with long-chain alcohols  Section 12.2 There Are Three Common Types of Membrane Lipids The common types of membrane lipids are as follows: – phospholipids – glycolipids – cholesterol Schematic Structure of a Glycerophospholipid Structure of Phosphatidate  Common Alcohols Used in Making Phosphoglycerides Phosphoglycerides are derived from phosphatidate by the formation of an ester bond between the phosphate and an alcohol.  Some Common Glycerophosphoglycerides Found in Membranes Ether-linked glycerophospholipid Ether-linked glycerophospholipid Galactolipids and sulfolipids – examples of glycerolipids with sugar head groups Example of archaeal bacterial structural lipid  Phospholipids May Also Be Built on a Sphingosine Platform Sphingomyelin is a common membrane lipid in which the primary hydroxyl group of sphingosine is esterified to phosphorylcholine. Sphingolipids – polar structural lipids - Sphingosine backbone - One fatty acyl chain – position 2 - Polar head group – position 1  Glycosphingolipids contain sugar head groups Glycolipids are carbohydrate-containing lipids derived from sphingosine. The carbohydrate is linked to the primary alcohol of sphingosine. Cerebrosides are the simplest glycolipids, containing only a single sugar (glucose or galactose). Gangliosides contain a branched chain of as many as seven sugar molecules. The carbohydrate components of glycolipids are on the extracellular surface of the cell membrane, where they play a role in cell–cell recognition. Cerebrosides Are Simple Glycolipids Gangliosides as Determinants of Blood Groups Specificities of phospholipases  Membrane Lipids areAmphipathic Molecules Containing a Hydrophilic and a Hydrophobic Moiety Membrane lipids are amphipathic molecules, containing hydrophobic and hydrophilic properties. The fatty acid tail components provide the hydrophobic properties, whereas the alcohol and phosphate components, called the polar head group, provide the hydrophilic properties. Representations of Membrane Lipids Terpenes – distinguished by the number of isoprene units they contain 2-methyl-1,3-butadiene Fig 5.14 Monoterpenes, triterpenes and their derivatives Reproduced from: Biochemistry by T.A. Brown, ISBN: 9781907904288 © Scion Cholesterol – essential component of animal membrane – a sterol formed by cyclization of squalene – a triterpene Plant version is called stigmasterol  Cholesterol is a Lipid Based on a Steroid Nucleus Cholesterol is a steroid that is modified on one end by the attachment of a fatty acid chain and at the other end by a hydroxyl group. In membranes, the hydroxyl group interacts with phospholipid head groups. Can you predict the orientation of cholesterol in the plasma membrane Cholesterol –precursor for various steroid hormones Table 5.3 Steroid hormones, derivatives of sterol Reproduced from: Biochemistry by T.A. Brown, ISBN: 9781907904288 © Scion Fig 5.18 Lipid vitamins – Isoprenoid compounds