Biological molecules

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  • Created by: ZoeKing98
  • Created on: 06-05-16 14:38
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  • Biological molecules
    • Protein
      • Monomers amino acids
        • Polymer: polypeptide joined during polymerisation by peptide bonds
        • Amine group
        • Carboxyl group
        • 'R' group
        • 20 amino acids
      • Primary structure: sequence of amino acids, specfic for each protein
        • Secondary structure: type of folding (e.g. beta pleated sheets or alpha helix)
          • Tertiary structure: 3D shape after further folding
            • Quaternary structure: more than one tertiary structures coming together
              • Sometimes has a prosthetic group (e.g. iron ions in a haem group)
            • Hyorogen bonds are numerous but easily broken
            • Strong disulfide bridges can form
            • Ionic bonds can form between unbonded caroboxyl and amine groups, broken by pH changes
          • Occurs due to attraction from poles forming hydrogen bonds between N and O in the amine and carboxyl groups
        • Determined by DNA
    • Water
      • Polar - oxygen slightly negative and hydrogens slightly positive
      • Two sets of lone pairs
      • Can form hydrogen bonds
      • Bond angle 104.5 degrees
      • Cohesion between molecules ('sticking' together)
      • High laten heat of vaporisation and fusion
      • Solvent
      • High specific heat capacity
      • Metabolite - breaks down and builds up molecules / compoufnds
    • Carbohydrates
      • Monomer: monosaccharide
        • Fructose
          • Form sucrose together
            • Glucose (alpha and beta)
              • 2 together form maltose
              • Form lactose together
        • Galactose
          • Form lactose together
        • Glucose (alpha and beta)
          • 2 together form maltose
      • Polymer: polysaccharide
        • Starch
          • Amylose
            • Coiled alpha glucose held together by hydrogen bonds (1-4 glycosidic bonds allow the coiled structure)
          • Amylopectin
            • Branched alpha glucose (1-6 glycosidic bonds allowing branching)
          • Insoluble - has no effect on water potential
        • Glycogen
          • Branched
          • Energy storage for animals
        • Cellulose
          • Structrual in plants
          • Beta glucose bonded in altervative orientations
        • Monomers bonded by glycosidic bonds
          • Condensation reaction occurs (water molecule is formed)
          • Bonds broken by hydrolysis - addition of water
    • Lipids
      • Monomers: glycerol and fatty acids
        • Polymer: typically 1 glycerol group and three fatty acid 'tails' - triglycerides
          • Saturated - all single bonds. Typically solid at room temp (fat)
          • Unsaturated - mono: 1 double bond; poly: more than 1. Typically liquid at room temp (oils)
          • Low mass to energy ratio so 'light' to carry
        • Phospholipid polymer: 1 glycerol, 2 fatty acids and a phosphate group - found in membranes
          • Hydrophobic 'tail'
          • Hydrophilic 'head'
          • Polar
        • Ester bonds between glycerol and fatty acids
      • Insoluble in water (so no effect on WP); soluble in organic solvents
      • Energy source
      • Waterproofing e.g. waxy cuticle
      • Insulation
      • Protection
      • Triglycerides: high ratio of hydrogen to oxygen means an important source of water
      • Emulsion test: add 5cm ethanol to 2cm liquid sample and shake before adding 5cm of water. A cloudy white precipitate indicates the presence of a lipid.

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