Chapter Five; Fats, Oils, and Other Lipids
Chapter Five; Fats, Oils, and Other Lipids BIO 1050
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This 5 page Class Notes was uploaded by Amber Notetaker on Friday September 23, 2016. The Class Notes belongs to BIO 1050 at Wright State University taught by Amy Wissman in Fall 2016. Since its upload, it has received 181 views. For similar materials see Biology of Food in Biology at Wright State University.
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Date Created: 09/23/16
Chapter 5 What Are Lipids And Why Do We Need Them? o Lipids: category of compounds containing carbon, hydrogen and oxygen that are hydrophobic (insoluble in water) o Perform important functions in the body: Energy storage Insulation Protein transporter in blood (lipoproteins) Cell membrane o Heart and muscle use fatty acid for ENERGY Three Types of Lipids: Triglycerides, o Fatty Acids Phospholipids o Fatty Acids Sterols o Four rings of C H Basic unit of triglycerides and phospholipids= fatty acids o Triglyceride: 3 fatty acids connected to glycerol bone Most common lipid found in food and body Referred to as FATS o Phospholipids: glycerol backbone, two fatty acids and a phosphorous group Phosphorus- containing head is hydrophilic Fatty acid tail is hydrophobic Cell membranes made of phospholipid bilayer Lecithin is an emulsifier o In Body: part of bile o In Foods: Natural (eggs) or added in foods (in dressing) Lipoproteins- transport some fats in blood o Phospholipid + protein= lipidprotein o Sterols: four connecting rings of carbon and hydrogen Example: cholesterol Important role in cell membrane structure Precursor of important compounds in body Not required in diet since body makes all cholesterol needed. Structure of a Fatty Acid: o -Chain of carbon and hydrogen atoms o Acid group (-COOH) at one end o Fatty acid can vary by: Length of chain Whether carbons have any double bonds between them (or all single bonds) Total number of double bonds Two Categories of Fatty Acid o Saturated fatty acids: -All carbons in chain single bonded C-C-C-C-C (straight) Solid at room temperature o Unsaturated Fatty Acids: -1 or more double bond between carbons (less saturated with H’s) More liquid at room temperature (kinked carbon chain) 2 Types of Unsaturated Fatty Acids: o Monounsaturated Fatty Acid (MUFA): One C=C double bond Example: Oleic acid, 18 C (olive oil) o Polyunsaturated Fatty Acid (PUFA): >1 C+C double bond Example: essential (-something you need to get from food because your body does not produce it.) fatty acids (EFA’s) Linoleic and alpha-linlenic acid Digesting Fats: o Mouth-ligual lipase o Stomach- gastric lipase o Small Intestine- pancreatic lipase (fatty acid and monoglycerides) helps by…. Bile acids: emulsifiers- break triglycerides down to smaller fat molecules and keep in watery solution Absorption: Micelles- fats absorb into intestinal cell Small chain fatty acid- go to blood Longer chain fatty acids enter lymphatic system- require transport molecule= chylomicron (phospholipids) What Happens When You Fat You Eat? o *Phospholipid + protein = Lipoprotein 3 Lipoproteins transport fat through the lymph and body. Different amounts of protein in each and each has a different role Chylomicrons Very low-density lipoproteins (VLDL): deliver fat made in liver to cells/tissues then converts to LDL. Low-density Lipoproteins (LDL “bad cholesterol): deposits cholesterol on wall of arteries High-density Lipoproteins (HDL “good”)- remove cholesterol from body and deliver to liver to excretion. Essential Fatty Acids: o Body can’t make on its own. Helps keep cell membranes healthy Make eicosanoids (local acting hormones-like subst) o Types: Linoleic Acids used to make arachidonic acid (precursor of omega-6) Alpha-Linolenic Acid (omega-3 fatty acid: Limited amount can be converted into EPA and DHA: heart and brain healthy omega- 3 fatty acid found in fatty fish. What Are The Best Food Sources of Fats? o Sources of Unsaturated Fats: Vegetable oils (olive and canola) Soybeans, walnuts, flaxseeds, and wheat germ o Limited Sources of Saturated Fats: Animal sources: fatty meats, whole-milk dairy products, and skin on poultry. Plant sources: coconut, palm, palm kernel oil. What is ‘Trans-fat’? 4 o Cis- hydrogens are on the same side of the double bond o Trans- hydrogens are on opposite sides of the double bond What is Heart Disease and What Increases Your Risk? o Heart disease begins with the buildup in the arteries. Atherosclerosis: narrowing of arteries due to buildup of plaque (hardened fat and cell debris) Injury to lining of arteries, contributed by high blood pressure, high cholesterol levels, and smoking. 5
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