Lipids mind map

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  • Lipids
    • A group of substances containing a large amount of carbon and hydrogen that are soluble in alcohol instead of water because they are non-polar molecules
    • Triglycerides
      • Lipids made of one glycerol molecule and 3 fatty acids joined by ester bonds
      • Energy source - can be respired to release ATP
      • Energy store - insoluble in water and high proportion of hydrogen means that 1g of fat releases twice the amount of energy as 1g of glucose
      • Insulation - the adipose tissues of animals store lipids for insulation
      • Buoyancy - fat is less dense than water and so can help animals float
      • Protection - can form a layer of mechanical insulation around delicate organs
    • Phospholipids
      • A glycerol molecule bonded to two fatty acids and one phosphate group
      • They are found in cell membranes in the phospholipid bilayer
      • The phosphate group is the head of the molecule and is hydrophilic so dissolves on the outside of the bilayer
      • The fatty acid tails are hydrophobic so form a barrier that water-soluble molecules cannot pass across
    • Cholestorol
      • A polar molecule consisting of hydrocarbon rings attached to a hydrocarbon tail
      • A relatively small molecule with a fat shape
      • Can fit into the phospholipid bilayer to strengthen it, making it less fluid
    • Glycolipids - carbohydrate attached to a lipid with a glycosidic bond
    • Fatty acids
      • Saturated: there are no C=C double bonds and the molecule has as many hydrogen atoms as is possible
      • Unsaturated: there is at least one C=C double bond (1 bond would be mono unsaturated, more C=C bonds would make a polyunsaturated fat) and, as a result, the molecule contains fewer hydrogen atoms
      • C=C double bonds are kinked and so an unsaturated fatty acid takes up more space than a saturated fatty acid. This means that unsaturated fats have lower melting points
    • Ester bonds
      • Each glycerol molecule can form covalent ester bonds with up to three fatty acids
      • The reaction to form ester bonds is a condensation reaction - water is another product of the reaction and water is used when the bond is hydrolysed
      • The water molecule released is made from the OH group of the fatty acids and the hydrogen from an OH group from the glycerol

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