lipids

• 3 main types of lipids: triglycerides, phospholipids and steroids
• lipids are made up of carbon, oxygen and hydrogen in a smaller proportion to carbohydrates
• lipids are insoluble in water
• lipids are soluble in organic solvents such as alcohol and acetone
• each fatty acids consists of a carboxylic group COOH
• each fatty acid consists of a long hydrocarbon chain
• each fatty acid consists of a methyl group CH3
• fatty acids can be saturated, monosaturated and polysaturated
• saturated - no double bonds between carbon atoms
• monosaturated - only one double bond between carbon atoms
• polysaturated - more than one double bond between carbon atoms
• unsaturated fatty acids can be cis or trans
• cis = hydrogen atoms on the same side of a double bond
• trans = hydrogen atoms are on opposite side of a double bond
• triglycerides are formed from one molecule of glycerol and 3 fatty acids
• in triglycerides fatty acids bond to the glycerol molecule by ester bonds in a condensation reaction
• in all triglycerides, the glycerol molecule is the same so the differences in properties come from the variations in fatty acids (over 70)
• triglycerides have a high ratio of energy storing carbon-hydrogen bonds to carbon atoms and therefore are excellent stores of energy