Lipids Dossier PDF

# Lipids ## Classification * **Lipids with fatty acids** * **Saponifiable** * **Simple** * **Acylglycerols** * **Cerides** * **Complex** * **Phosphoglycerides** * **Phospholipids** * **Glycosphingolipi...

# Lipids ## Classification * **Lipids with fatty acids** * **Saponifiable** * **Simple** * **Acylglycerols** * **Cerides** * **Complex** * **Phosphoglycerides** * **Phospholipids** * **Glycosphingolipids** * **Phosphoinositol** * **Insaponifiable** * **Terpenes and isoprenoides** * **Steroids** * **Prostaglandins** ## Structure * **Full formula:** *CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-COOH* * **Condensed Formula:** *CH3(CH2)16COOH* * **Model with angles of 110 degrees:** ``` H2 H2 H2 H2 H2 H2 H₂ 12 H2 H₃C C C C C C C C C C C C C C C C COOH H2 H2 H2 H2 H2 H2 H2 H2 ``` * **Simplified model:** *CH2*s are simplified in the model. * **Compact model:** * Hydrogen and Oxygen atoms are represented with different colors: * Black - Carbon * Red - Oxygen * White - Hydrogen ## Fatty Acids * **Saturated fatty acids:** * All carbons are saturated * **Stearic acid** is an example. * **Unsaturated fatty acids:** * At least one double bond in the chain (can have more than one double bond) * **Oleic acid** is an example. * **Cis** - hydrogen atoms on the same side of the double bond. * **Trans** - hydrogen atoms on the opposite side of the double bond. ## Fatty Acids Examples * **Palmitic acid (C16:0)**: *CH3(CH2)14COOH* * **Stearic acid (C18:0)**: *CH3(CH2)16COOH* * **Oleic acid (C18:1∆9)**: *CH3(CH2)7CH=CH(CH2)7COOH* * **Linoleic acid (C18:2∆9,12)**: *CH3(CH2)4CH=CHCH2CH=CH(CH2)7COOH* ## Esterification and Saponification * **Esterification:** Reaction that forms triacylglycerol, an ester of glycerol and three fatty acids. * Accomplish by reacting acid with alcohol in the presence of a catalyst (strong acid, usually H2SO4). * **Saponification:** Reaction of triacylglycerol with a strong base to produce glycerol and salts of fatty acids. * The salts formed are called soaps. ## Manufacturing of Soap * **Oils (triglycerides) react with strong bases (lye - NaOH or Potassium hydroxide - KOH) to form soap and glycerol.* ## Glycerols * **Glycerol:** Three hydroxyl groups are attached to a three-carbon chain. * **Monoacylglycerol:** Glycerol with one fatty acid attached. * **Diacylglycerol:** Glycerol with two fatty acids attached. * **Triacylglycerol (triglyceride):** Glycerol with three fatty acids attached. This is how fatty acids are stored in the human body. ## Structure of Fats * **Head**: The polar part of the molecule. * **Tail:** The nonpolar part of the molecule. ## Phospholipids * **Phospholipids** are the most abundant in cell membranes. * **Phospholipids** are composed of: * **Glycerol backbone** * **Two fatty acids** * **Phosphate group** * **The phosphate group** is linked with another polar molecule. * **Phospholipids are amphipathic:** * Polar heads and non-polar tails. * Form **micelles** (circular structures) with nonpolar tails inside and polar heads on the outside. ## Different Types of Phospholipids * **Phosphatidylethanolamine**: has an ethanolamine group. * **Phosphatidylserine**: has a serine group. * **Phosphatidylcholine**: has a choline group. * **Sphingomyelin**: has a choline group but lacks glycerol. ## Steroids * **Steroids:** are lipids that are formed by four ring structures. * **Cholesterol** is an important component of cell membranes. It creates stability and fluidity. * Some steroids are **hormones**. * **Estradiol (estrogen)** is an example. ## Diagram The image shows a diagram of a cell membrane. It is composed of a **phospholipid bilayer** with: * **Hydrophilic heads** facing the outside of the membrane and the inside of the cell. * **Hydrophobic tails** facing the inside of the membrane. * **Proteins** embedded within the membrane. This structure creates a barrier that allows the cell to maintain its internal environment.