PHTH1011 Lipids Definition, Types and Functions PDF

Summary

This document covers the definition, types, and functions of lipids. It details various types, including fatty acids, triglycerides, phospholipids, glycolipids, and sterols. The presentation also includes discussions on cholesterol, bile salts, and lipid profiles.

Full Transcript

PHTH1011 Lipids Definition, Types and Functions by Professor Rachael Irving Objectives ▪ Defining the structures of common types of lipids ▪ Outlining the basic functions of lipids ▪ Looking at the inter-play of structure and function ▪ Understanding the role of bimolecular sheets in gaseous exchang...

PHTH1011 Lipids Definition, Types and Functions by Professor Rachael Irving Objectives ▪ Defining the structures of common types of lipids ▪ Outlining the basic functions of lipids ▪ Looking at the inter-play of structure and function ▪ Understanding the role of bimolecular sheets in gaseous exchange ▪ Be able to name a few diseases associated with lipid storage Lipids(definition) 1. Li lipids are a chemically diverse group of organic compounds, the common and defining feature of which is their insolubility in water. 1. A lipid can therefore be defined as any fat-soluble , organic molecule. 2. A lipid is highly soluble in non-polar solvents (Chloroform and ether). 3. lipids water-insolubility contributes to much of the complexity in their digestion, transport, and metabolism (functions). 4. Lipids are essential to the overall energy economy of the cell. Types of Lipids : 1. (Fatty acids) ▪Fatty acids are long hydrocarbon chains of various length and degrees of un-saturation terminating with carboxylic acid groups. ▪Fatty acids carbon atoms are numbered starting at the Carboxyl terminus. ▪The systematic name is derived from the name of its parent hydrocarbon by the substitution of oic for the final e. ▪For example C18 saturated fatty acid is called octadecanoic because the parent hydrocarbon is octadecane. A C18 fatty acid with one double bond is called octadecenoic. Example of Fatty Acids : Octadecadienoic Acid Saturated/Unsaturated Fatty Acids Saturated fatty acids : Fatty acids with have no double bonds. They carry the maximum possible number of hydrogen atoms. Example Stearic Acid. Unsaturated fatty acids : Fatty acids that lack hydrogen atoms and have at least one double bonds. Example Linoleic Acid. Cis and trans-Fatty Acids ▪A cis fatty acid has its hydrogen atoms on the same side of the double bonds. ▪A trans- fatty acids has its hydrogen atoms on opposite side of the double bond. Essential/Non-Essential Fatty Acids. ▪Non-essential Fatty Acids are produced by the body. ▪Essential Fatty Acids are derived from the diets, these acids are not produced by the body but are necessary for vital functions. Examples linoleic (C18 : 2 ω6) and αlinolenic (C18 : 3 ω3). 2. (Triglycerides) ▪A triglyceride is formed from a molecule of glycerol and three fatty acids. ▪Triglycerides are major components of very low density lipoprotein (VLDL) and chylomicrons. ▪Triglycerides are important in metabolism as energy sources and transporters of dietary fat. 3. (Phospholipids) ▪ Phospholipids contain one or more fatty acids. The fatty acid is attached to, a phosphate and an alcohol. ▪ Phospholipids may be attached to glycerol, a 3 carbon alcohol or sphingosine. Sphingosine is an amino alcohol with a long unsaturated hydrocarbon carbon chain. ▪ Those Phospholipids derived from glycerols are called phosphoglycerides. Example cardiolipin found in the heart. ▪ Those derived from sphingosine is called Sphingomyelin. Sphingomyelin is found in the brain. 4. (Glycolipids) ▪Glycolipids are sugar containing lipids. ▪Glycolipids are derived from sphingosine. ▪Glycolipids differ from sphingomyelin in the identity of the unit that is linked to the primary hydroxyl group of the sphingosine backbone. The simplest glycolipid is called a cerebroside. It contains a sugar residue of glucose or galactose. ▪ Cerebroside is found in neural tissue. 5. Sterol lipids : (1)Cholesterol ▪ Cholesterol is built from 4 linked hydrocarbon rings. ▪ A hydrocarbon tail is linked to the steroid at one end and a hydroxyl group is attached at the other end. ▪ In membranes, the orientation of the molecule is parallel to the fatty acids chains of the Phospholipids and the hydroxyl group interacts with the nearby Phospholipid head groups. Structure of Cholesterol: 4 linked hydrocarbon rings Sterol Lipids: (2)Bile Salt Bile Salt has the 4 linked hydrocarbon rings plus : Taurine or Glycine or Both Example of Bile Salt Originates from cholesterol. Lipid Profile High Density lipoprotein Cholesterol-HDL-C (>1.2mmol/l Low Density Lipoprotein Cholesterol -LDL-C (2.4mmol/l) Triglyceride (

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