Cards (12)

    • Features of saturated fatty acids
      • contain only single bonds
      • Single chain molecules- have many contact points
      • Higher melting points = solid at room temperature
      • Found in animal fats
    • Features of triglycerides
      • energy storage = large ratio of energy storing carbon - hydrogen bonds compared to number of carbon atoms
      • Act as metabolic water source = high ratio of hydrogen to oxygen atoms, can release water if oxidised
      • Don’t affect water potential and osmosis, large and hydrophobic so insoluble in water
      • Lipids have low mass= store a lot without increasing mass and preventing movement
    • Features of unsaturated fatty acids
      • contain C=C double bonds- kinked molecules have fewer contact points
      • Lower melting point = liquid at room temperature
      • Found in plant oils
    • Functions of membranes in cells
      • provide internal transport system= selectively permeable to regulate passage of molecules into and out of organelles
      • Provide reaction surface = isolate organelles from cytoplasm for specific metabolic reactions
    • How are triglycerides formed
      Condensation of one molecule of glycerol and three molecules of fatty acids
    • Two groups of lipids
      • triglycerides
      • Phospholipids
    • What bond forms during the condensation reaction between a glycerol and a fatty acid
      Ester bond
    • Test for lipids
      • dissolve solid samples in ethanol
      • Add equal volume of water and shake
      • Positive result= milky white emulsion forms
    • Phospholipids are made up of two fatty acids and a phosphate group attached to a glycerol backbone.
    • Phospholipid bilayers form the membranes that surround cells and organelles.
    • Cholesterol is an important component of cell membranes as it helps to maintain their fluidity at different temperatures.
    • Function of phospholipids
      • Contain a hydrophobic tail and hydrophylic phosphate head - form a bilayer within cell Surface membranes in aqueous environments
      • Hydrophilic head helps hold at the surface of cell surface membrane
      • Phospholipid structure allows them to make glycolipids by combining with carbohydrates within the cell surface membrane- glycolipids important in cell recognition
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