Lipids PDF

Lipids long term energy storage concentrated energy OBJECTIVE Differentiate between condensation and hydrolysis. Describe the molecular structure of triglycerides. Describe...

Lipids long term energy storage concentrated energy OBJECTIVE Differentiate between condensation and hydrolysis. Describe the molecular structure of triglycerides. Describe the role of triglycerides as a source of energy. Describe the molecular structure of phospholipids. S Describe the role of phospholipids in membrane structure and function.  LIPIDS Lipids are composed of C, H, O long hydrocarbon chains (H- C-) Less oxygen than carbohydrates hence less reactive (usually 6 oxygen atoms) Do not form polymers big molecules made of smaller subunits not a continuing chain TYPES OF LIPIDS 2. 1. Phospholipid Triglycerides s TRIGLYCERIDES TRIGLYCERIDES Triglycerides – Fats & Oils Predominant Major storage Structure form of fat in form of fat in 3 fatty acids + foods the body glycerol FATTY ACIDS and FATS A fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. FATTY ACIDS ▪ Fatty Acids – carbon chains vary in: 1. Length – affects absorption 2. Saturation –chemical structure; affects cooking & storage properties and health Saturated fats All C bonded to H No C=C double bonds long, straight chain most animal fats solid at room temp. contributes to cardiovascular disease (atherosclerosis) = plaque deposits  Unsaturated fats C=C double bonds in the fatty acids plant & fish fats vegetable oils liquid at room temperature the kinks made by double bonded C prevent the molecules from packing tightly together mono-unsaturated? poly-unsaturated?  Building Fats Triglycerides or Triacylglycerol 3 fatty acids linked to glycerol Building Fats Triglycerides or Triacylglycerol 3 fatty acids linked to glycerol ester linkage = between OH & COOH hydroxyl carboxyl TRIGLYCERIDES  Affects stability and protects against oxidation; more “shelf-stable” Widely used by food industry in margarine, shortening, peanut butter, baked goods & snack food DIGESTION, FUNCTIONS AND HEALTH EFFECTS OF TRIGLYCERIDES  Functions of triglycerides In the body, fats provide: 1. Energy – 9 kcal/gm A. Supplies 60% of body’s energy needs at rest B. Stored as adipose tissue 2. Insulation & protection 3. Metabolic water upon hydrolysis 4. Contribute flavor, aroma, and tenderness 5. Provide satiety 6. Carry fat-soluble vitamins (A,D,E & K)  Health Effects of Lipids Excess fat intake contributes to many diseases including: 1. Obesity 2. Diabetes 3. Cancer 4. Heart disease ▪ How? 1. High fat diets = high kcal diets 2. High saturated fat intake raises blood cholesterol 3. High fat intakes may promote cancer 4. Plaques in artery leading to atherosclerosis  Risks from trans fats Health Effects Risks from of cholesterol Lipids Risks from saturated fats  Benefits from monounsaturated fats and polyunsaturated fats Benefits from May reduce blood omega-6 and cholesterol & help prevent omega-3 fats cancer HEALTH EFFECTS OF LIPIDS Heart-Healthy Choices Saturated vs. unsaturated saturated unsaturated ✔ PHOSPHOLIPID S  PHOSPHOLIPID S 1. Similar to triglycerides in structure 2. Contains 2 fatty acids + phosphoric acid 3. Phospholipids in foods: Lecithin, egg yolks, soybeans, wheat germ, peanuts Amphipathic molecule ▪ Hydrophilic and ▪ Hydrophobic ends Phospholipids Phospholipids  Phospholipid s 1. Functions: part of cell membranes and acts as an emulsifier (helps keep fats in solution) 2. Not a dietary essential; made by the liver Role in membrane TRIGLYCERIDES vs PHOSPHOLIPIDS TRIGLYCERIDES vs PHOSPHOLIPIDS