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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Phospolipids
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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triglycerides
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
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