NUTR 251 Study Guide EXAM 2 Lipids Chapter 5 1 Be able to distinguish differences and similarities between saturated vs monounsaturated vs polyunsaturated o 1 saturated all carbon atoms must make four bonds with neighboring atoms there are only single bonds Solid at room temperature SSSS saturated single solid stearic acid 2 Monounsaturated has one double bond in its structure Kink in the chain unsaturated C atoms are not fully saturated with H atoms at one point Oleic acid is an example Liquid at room temperature 3 Polyunsaturated has two or more double bonds in its structure Liquid at room temperature Linoleic acid is an example o linolenic vs linoleic vs DHA and EPA 1 Linolenic when the first double bond is between the third and fourth carbons from the methyl carbon it is designated an omega 3 fatty acid Linoleic when the first double bond is 6 carbons out from the methyl carbon it is designated an omega 6 fatty acid 2 Linoleic and linolenic acids are essential in their role in membrane structure They are precursors to other fatty acids and eicosanoids use to synthesis other fatty acids 3 Linoleic rich in leafy vegetables grains nuts seeds and vegetable oils Linolenic rich in fats and oils from canola soybean walnut flaxseed salmon and wheat germ 4 EPA and DHA are two long chain omega 3 fatty acids that can be synthesized in the body s cells from linolenic acid Linolenic is a precursor to EPA and DHA 5 Rich in fatty fish supplements breast milk o cis fatty acids vs trans fatty acids 1 Cis has its hydrogens on the same side of the double bond cis molecules bend into a U like formation Most naturally occurring unsaturated fatty acids in foods are cis 2 Trans has its hydrogens on the opposite sides of the double bond trans molecules are more linear The trans form typically occurs in partially hydrogenated foods when hydrogen atoms shift around some double bonds and change the configuration from cis to trans o Hydrogenation stabilizes polyunsaturated fats by adding hydrogen thus converting them to saturated fatty acids Unsaturated fatty acids have a higher chance of becoming spoiled they are unstable prostaglandins vs essential fatty acids o 1 Prostaglandins decrease blood clotting decrease inflammation part of membrane structure correlate to heart health Hypothesis prostaglandins decrease coronary heart disease risk Linolenic acid EPA synthesis of eicosanoids prostaglandin 2 Essential FA the body cannot make it They must be supplied by the diet The body cannot make linoleic and linolenic acid tropical oils palm and coconut vs corn oil o 1 Tropical oils palm and coconut they are major sources of saturated fats The products that contain them are candies pastries pies doughnuts and cookies Coconut oil contains a lot more saturated fatty acids than palm Animal fats and the tropical oils of coconut and palm contain mostly saturated fatty acids 2 Corn oil have way less than half saturated fatty acids Mainly contains polyunsaturated omega 6 fatty acids Many vegetable oils are rich in omega 6 Linoleic acid polyunsaturated and other food sources are sunflower safflower and soybean oils o phospholipid vs triglyceride 1 phospholipid they are similar in structure to triglycerides except a phosphorylated alcohol replaces one fatty acid chain Best known is lecithin Lecithin has one glycerol with two of its three attachment sites occupied by fatty acids like those in triglycerides A phosphate group and a molecule of choline occupy the third site The hydrophobic fatty acids make phospholipids soluble in fat the hydrophilic phosphate group allows them to dissolve in water This enables the food industry to use phospholipids as emulsifiers to mix fats with water in such products as mayonnaise salad dressing and candy bars They are found naturally in foods The richest in lecithin are eggs liver soybeans wheat germ and peanuts Lecithin and other phospholipids are constituents of cell membranes They are soluble in both water and fat and they can help fat soluble substances including vitamins and hormones to pass easily in and out of cells They are digested due to their fatty acids being removed by hydrolysis The newly made triglyceride and other lipids cholesterol and phospholipids are packed with protein into transport vehicles known as chylomicrons 2 Triglyceride it is composed of a 3 carbon glycerol backbone with three fatty acids extending out from each of the carbons of glycerol Three fatty acids attached to a glycerol form a triglyceride and yield water To make triglyceride three fatty acids attach to glycerol in a condensation reaction They release water They are most abundant both in foods and in the body Few fatty acids occur free in foods or in the body because they are mostly incorporated into triglycerides To make a triglyceride a series of condensation reactions combine a hydrogen atom from the glycerol and a hydroxyl OH group from a fatty acid forming a molecule of water and leaving a bond between the two molecules Most triglycerides contain a mixture of more than one type of fatty acid A monounsaturated fat polyunsaturated saturated and unsaturated fat is composed of triglycerides in which most of the fatty acids will be that category of fatty acid Triglycerides are found in all fat foods Goal of fat digestion is to dismantle triglycerides into small molecules that the body can absorb and use Most of the hydrolysis of triglycerides occurs in the small intestine Newly made triglycerides and other lipids are packed with protein into transport vehicles known as chylomicrons Triglycerides provide the cells with energy when someone is active their meals triglycerides provide some of the fuel that keeps them moving and when a person loses their appetite their stored triglycerides fuel much of their body s work until they can eat again Blood lipid profile suggests consuming 150mg dL of triglycerides 3 Use of chylomicrons The cells take triglycerides cholesterol and phospholipids to use for energy make hormones or other compounds or build new membranes 2 Lipids provide 9 kilocalories gram 3 Identify foods that are rich sources for saturated monounsaturated and polyunsaturated fatty acids both omega 3 and omega 6 fatty acids o Saturated beef meat butter dairy palm oil coconut oil exceptions to these two oils o Monounsaturated canola oil olive oil milk and beef nuts avocados and peanuts o Triglyceride mixture of both unsaturated and saturated fatty acids ex beef o Polyunsaturated oils nuts and