2Lipids Lipids are composed of C, H, O 4 groups: Do not form polymers fatsoilswaxessteroidsDo not form polymersbig molecules made of smaller subunitsnot a continuing chainMade of same elements as carbohydrates but very different structure/ proportions & therefore very different biological properties
3Lipids Six functions of lipids: 1. Long term energy storage 2. Protection against heat loss(insulation)3. Protection against physical shock4. Protection against water loss5. Chemical messengers (hormones)6. Major component of membranes(phospholipids)Made of same elements as carbohydrates but very different structure/ proportions & therefore very different biological properties
4Why do humans like fatty foods? Fats store energyFunction:energy storage2x energy ofcarbohydratescushion organsinsulates bodythink whale blubber!What happens when you add oil to waterWhy is there a lot of energy stored in fats?• big molecule• lots of bonds of stored energySo why are we attracted to eating fat?Think about our ancestors on the Serengeti Plain & during the Ice Age. Was eating fat an advantage?
5dehydration synthesis Fat subunitsStructure:glycerol (3C alcohol) + fatty acidfatty acid = long “tail” with COOH group at “head”Look at structure… What makes them hydrophobic?Note functional group = carboxyldehydration synthesis
6Fatty Acid Structure Carboxyl group (COOH) forms the acid. “R” group is a hydrocarbon chain (chain of hydrogens and carbons).
7A Representative Fatty Acid CarboxylGroupHydrocarbon Group
10Hydrophilic vs hydrophobic Hydrophilic – Water loving – soluble in waterHydrophobic – water hating – is NOTsoluble in waterTriglyceride =1 glycerol, 3 fatty acidsHydrophilicPhospholipids = 1 glycerol,2 fatty acids 1 phosphate grouptails are hydrophobicthe heads are hydrophilic.make up cell membranes
11Saturated fats All C bonded to H No C=C double bonds long, straight chainmost animal fatssolid at room temp.contributes to cardiovascular disease (atherosclerosis) = plaque depositsMostly animal fats
13Unsaturated fats C=C double bonds in the fatty acids plant & fish fats vegetable oilsliquid at room temperaturethe kinks made by double bonded C prevent the molecules from packing tightly togetherMostly plant lipidsThink about “natural” peanut butter:Lots of unsaturated fats Oil separates outCompanies want to make their product easier to use:Stop the oil from separating Keep oil solid at room temp.Hydrogenate it = chemically alter to saturate itAffect nutrition?mono-unsaturated?poly-unsaturated?
15If fatty acids are unsaturated, their shape is altered from a saturated molecule so the molecules in the Lipid push apart, thus making it more fluid and oily.Animals tend to have more saturated, and consequently solid at room temperature lipids whereas plants tend to have more unsaturated and so fluid at room temperature lipids
16Waxes Ear wax – protection from foreign materials/ invaders (such as insects)Wax coating on leaves – forms a barrier to keep waterin leaves
17Steroids Cholesterol Hormones (chemical messengers) Found in cell membranes – keeps them flexibleHormones (chemical messengers)
18Quiz What are the four types of lipids ? Name as many functions of lipids as possible (6).What is the difference in saturated & unsaturated ?How could you tell the difference in saturated & unsaturated by looking at an item ?What is healthier, saturated or unsaturated fats ?Lipids contain more energy than carbs, so why are carbs are primary energy source ?What is the monomer & polymer of lipids ?Structurally, how do you tell the difference in carbs & lipids ?
19Answers Fats, oils, waxes, & steroids Energy storage, insulation, protection from water loss, protection against physical shocks, chemical messengers, component of cell membranesC=C double bonds are in unsaturatedSaturated are solid at room temp., unsaturated are liquid at room temp.unsaturatedLipids are harder to break down, because they are insoluble in waterTechnically, there are not monomers & polymersBoth contain C,H, & O, but in carbs they are in a 1:2:1 ratio