Lipids/Triglycerides/Phospholipids/Cholestrol

    Cards (28)

    • Lipids
      Macromolecules that contain carbon, hydrogen and oxygen atoms
    • Lipids
      • Non-polar and hydrophobic
      • Two groups: Triglycerides and phospholipids
    • Triglycerides
      • Non polar, hydrophobic molecules
      • Monomers are glycerol and fatty acids
    • Glycerol
      An alcohol which is an organic molecule containing a hydroxyl group bonded to a carbon atom
    • Fatty acids

      • Contain a methyl group at one end of a hydrocarbon chain known as the R group, and a carboxyl group at the other side
      • Shorthand chemical formula is RCOOH
    • Fatty acids

      • Length of the hydrocarbon chain (R group) determines how likely it is to mix with water
      • Can be saturated (mainly in animal fat) or unsaturated (mainly vegetable oils)
    • Saturated fatty acids

      Hydrocarbon chain has only single bonds between carbons
    • Unsaturated fatty acids

      Hydrocarbon chain consists of at least one double bond between carbons
    • Triglycerides
      • Energy storage: Serve as a long-term energy storage molecule
      • Insulation: Act as insulation, helping maintain body temperature
      • Protection: Cushion and protect vital organs
      • Have a relatively low mass, so a lot can be stored without increasing mass and preventing movement
    • Phospholipids
      In water, position themselves so that the hydrophilic head groups can interact with water molecules while the hydrophobic tails cluster together, away from water molecules. This structure is called a phospholipid bilayer.
    • Plasma membranes

      • Described as a fluid-mosaic model due to the mixture of phospholipids, proteins, glycoproteins and glycolipids
      • Partially permeable membrane, with molecules embedded either on the outside or through the phospholipid bilayer
    • Cholesterol
      • Part of a family of lipids called sterols
      • Has a hydrophilic hydroxyl group and a hydrophobic rest of the molecule
      • Can insert into cell membranes, with the hydroxyl group interacting with phospholipid head groups and the hydrophobic part interacting with fatty acid tails
      • Plays a key role in controlling the fluidity of cell membranes
    • Cholesterol is used as the starting point for a range of hormones including oestrogen and testosterone
    • Cholesterol is used in the body to make vitamin D, and to produce bile in the liver to increase the rate of digestion of lipids by the enzyme lipase
    • Plasma membrane
      The membrane that surrounds cells and organelles
    • Plasma membrane structure
      • Fluid mosaic model
      • Mixture of different components (phospholipids, proteins, glycoproteins, glycolipids, cholesterol)
    • Phospholipid bilayer

      Two layers of phospholipids with hydrophilic heads facing outwards and hydrophobic tails facing inwards
    • Saturated fatty acid
      Fatty acid with no double bonds
    • Unsaturated fatty acid
      Fatty acid with double bonds
    • Cholesterol
      Restricts the lateral movement of molecules, making the membrane less fluid
    • Membrane proteins

      • Peripheral (attached to one side)
      • Integral (span the entire width)
    • Peripheral proteins

      Provide mechanical support or connect proteins to lipids/carbohydrates, often act as receptors
    • Integral proteins

      Protein carriers or channel proteins that transport molecules across the membrane
    • Partially permeable membrane

      Only certain molecules can diffuse through by simple diffusion (lipid-soluble, small, non-polar)
    • Larger, water-soluble, and polar molecules cannot pass through the membrane by simple diffusion
    • A phosphoglyceride has two fatty acids attached to one carbon atom on the glycerol backbone and one fatty acid attached to another carbon atom on the same molecule.
    • The polar head is called the glycerophosphate group, which contains phosphorus.
    • The hydrophobic tails are the fatty acid chains.