Lipids and Fats - Macromolecules PDF

If you’ve completed your quiz early, read pgs 21-24 on lipids & cbd LIPIDS AND FATS  Lipids – An introduction ◻ Includes: fats, phospholipids, steroids & waxes ◻ Contain C, H and O (but less Os than in carbohydrates) ◻ Insoluble in water Less OH bonds (polar) & more C-H bo...

If you’ve completed your quiz early, read pgs 21-24 on lipids & cbd LIPIDS AND FATS  Lipids – An introduction ◻ Includes: fats, phospholipids, steroids & waxes ◻ Contain C, H and O (but less Os than in carbohydrates) ◻ Insoluble in water Less OH bonds (polar) & more C-H bonds (non-polar than in carbs Lipids - Functions ◻ Used for: 1. Storing energy Stores more than 2x amount of chemical energy per gram than carbs or proteins 2. Building membranes 3. As chemical signalling membranes (hormones) 4. Insulation layers Lipids - Structure ◻ Not really a polymer but made of several large molecules joined together ◻ Made of 2 building blocks: 1. Glycerol: 2. Fatty acid: Lipids - Formation Esterification of a Triglyceride ◻ The hydroxyl group of one glycerol reacts with the carboxyl group of three fatty acids. ◻ The resulting bond is an ester linkage. Lipids – Esterfication rxn Lipids – Esterfication rxn Triglycerides Triglycerides = glycerol and 3 fatty acids formed by ester linkage (esterification) 1) Saturated Fats ◻ Usually come from animals. ◻ Solid at room temperature due to increased van der Waals attractions ◻ In animals, they are used for long-term energy storage, insulation, protection and helps dissolve fat soluble vitamins. ◻ All single bonds between carbon atoms. Triglycerides 2) Unsaturated Fats Usually comes from plant oils. Liquid at room temperature. One or more double bonds between carbon atoms. Rigid kinks reduce the number of van der Waals attractions Unsaturates vs. Saturates  Hydrogenation ◻ Hydrogenation is the industrial process by which hydrogen atoms are added to the double bonds of unsaturated triglycerides of liquid fats (corn oil or canola oil) to convert them into a semisolid material such as shortening or margarine. This increases shelf life and flavour stability. ◻ Hydrogenation causes the formation of trans fats (reconfigures the location of the H atoms in the fatty acid chain)…this increases the levels of cholesterol in the blood and increases the risk of heart disease. ◻ Watch video now! https://www.youtube.com/watch?v=KG_ybdk1VaE (3:09) Phospholipids ◻ Composed of one glycerol, two fatty acids and a highly polar phosphate group. ◻ Form cellular membranes (phospholipid bilayer). ◻ The phospholipid bilayer is virtually impermeable to macromolecules, relatively impermeable to charged ions, and quite permeable to small, lipid soluble molecules (it’s semipermeable!) Phospholipids Phospholipids ◻ O2 and CO2 diffuse through with very little resistance. ◻ Larger molecules pass through the membrane using various methods Steroids (+ Sterols) ◻ Composed of 4 fused hydrocarbon rings & functional groups. ◻ Have different functional groups attached to these rings ◻ Many act as chemical signallers (hormones) ◻ Ex. Cholesterol (sterol), testosterone, estrogen, progesterone. Waxes Long chain fatty acids linked to alcohols or carbon ring. Firm, pliable consistency, used as a waterproof coating. E.g. cutin on leaves Practice: Lipids section pgs 21-24 & cbd #13-17 pg 25