ch369_sum10_ch8_notes - Lipid . Defnition = A substance...

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Unformatted text preview: Lipid . Defnition = A substance that is relatively insoluble in water, and can be extracted From a cell with a non-polar solvent. Some lipids: atty acids . Triacylglycerols . Phospholipids . Cholesterol . Vitamins A,D,E,K . Sphingolipids. Todays topic - Lipids & membranes (Chapter 8) . Fatty acids ( FAs). Fatty acid Carboxylic acids with chains of varying lengths. 12 to 24 carbons are common, usually even numbers. pKa is about 4, so negative charge at physiological pH. Fatty acid Some common saturated fatty acids. ( saturated means no double bonds in carbon chain). palmitate stearate Laurate, 12 carbons. Myristate, 14 carbons. Palmitate, 16 carbons. Stearate, 18 carbons. Arachinate, 20 carbons. Some common unsaturated fatty acids. Linoleate (or linoleic acid), a polyunsaturated fatty acid. Oleate (or oleic acid), an unsaturated fatty acid. Unsaturated fatty acids can be either cis or trans isomer around double bond. Large majority of naturally occurring fatty acids are cis. Trans have higher melting point than cis (trans FAs pack together better, tend to form solids). Triacylglycerols (TAGs). Fatty acid (TAG) (FA) Tristearin (a simple triacylglycerol). A mixed triacylglycerol. FAs and TAGs store a lot of energy in a small volume . Denser energy storage than carbohydrates (fats can be packed together tightly without intervening water). Compare 38 kJ/g in fats versus 16 kJ/g in carbohydrates. Difference is because fats are more reduced (less oxidized) than carbohydrates (less oxidized = higher energy content). Fatty acids (FAs) and triacylglycerols (TAGs) Fats in a typical human diet. Animal fat. Example = lard (pig fat) The most abundant fatty acids in lard are palmitic & stearic acid. palmitic acid stearic acid Vegetable oil. linoleic acid oleic acid The most abundant fatty acids in canola oil are oleic acid (60%), linoleic acid (20%) and alpha linolenic acid (10%). Saturated fatty acids are only about 7% of canola oil. Brassica rapum is the source of rapeseed oil . Traditional plant breeding was used to create a seed that is rich in vegetable oil. Rapeseed oil is marketed as Canola oil . The canola oil name comes from Canada oil. Omega-3 means the frst double bond is on the 3rd carbon From the end oF the chain. alpha linolenic acid Omega-3 Fatty acids Alpha linolenic acid is very abundant in canola oil. Canola oil contains a lot oF omega-3 Fatty acid ; about 10% oF the Fatty acids in canola oil are omega-3. Essential fatty acids The omega-3 and omega-6 FAs are precursors for a number of important molecules. For example, prostaglandins are hormones that are synthesized from omega-6 fatty acids....
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ch369_sum10_ch8_notes - Lipid . Defnition = A substance...

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