Lipids AS Biology- for all

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To start off with...

  • lipids AKA fats( solid at room temp) and oils( liquid fats ant room temp) a few other things too 
  • they contain C,H,O twice as much H and half the amount of O than other organic compounds
  • formed by condenstations reactions which form ester bonds which release water when they form between the glycerol and fatty acids ( this is what a fat is broken down to in digestion this forms 3 molecules of water as three bonds are made per triglyceride
  • they are insouble in water because they are non polar but can be dissolved in ethanol
  • it releases x2 the amount of energy compared to carbohydrates per gram
  • waxes are similar to fats and oils but contain alcohol in them 
  • the general formula for a fatty acid is Cn H2n On where n is the nu,ber of C or O
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biological uses of Lipids

  • as an energy store
  • as a source of protection for internal organs 
  • lots of energy released when they are burnt and this helps to keep us warm 
  • waxes are used by plantsto form  a waxy cuticle on the outer layer of a leaf to help minimse the water loss from the plant 
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instead of having a glycerol base they have a phosphate group which is hydrophilic and polar where as the fatty acids are non polar and hydrophobic this is important in the formation of cell membranes as the polar parts from the outer part of a membrane and the hydrophobic part points in towards other hydro phbic parts

 i would recommend that you google pictures the structure of membranes and phospholipids as they is hard to explain accuratly !

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Testing for Lipids

this is called the Emulsion test

  • take 2cm of your sample
  • add to it 2cm of ethanol 
  •  shake 
  • in another test tube put water into it ( about 2cm ) and add your mixture to it 
  •  if your mixtures stays on top of the water you have a positive result and a Lipid is present
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saturated and unsaturated

staturated fats are bad for you  but what else do we know about them?

  • they only contain single bonds
  • they are saturated through the addition of hydrogen to fill the four valent spots Carbon has 
  • solid at room temperature most are animal fats
  • high melting points compared to unsat fats

Unsaturated fats 

  • liquid at room temperature
  • tend to come from plants
  • lower melting point compared to sat fats
  • form one or more double bonds with a carbon bonded to a carbon 
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  • they are made up of three fatty acids which can be saturated or unsaturated long or short
  • it is made with a glycerol backbone to which the fatty acids are attached 
  • when they are formed they produced 3 molecules of water 
  • they are used as an energy store for respiration
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Chloe Thorn

sorry about the blank one !

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