Carbohydrates

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  • Created by: Mazza24
  • Created on: 15-11-15 16:49
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  • Carbohydrates
    • Disaccharides
      • Are formed when two monosaccharides bond together via a condensation reaction and can be reversed via hydrolysis.
        • Important Disaccharides
          • Sucrose
          • Maltose
        • Condensation
          • forms a glycosidic bond by removing water causing two monosaccharides to bond forming a disaccharide.
          • this reaction forms a 1,,4 glycosidic bond
          • Removes the hydroxyl group from C1 and the hyrdrogen from C4 in another monomer to form water
        • hydrolysis
          • When a disaccharide is broken down into its two former monosaccharides by adding water.
          • These reactions are important in the digestion of food
          • Essentially does the opposite of condesation
    • Monosaccharides
      • basic carbohydrate monomers, i.e. single sugars. these are basic subunits of complex polysaccharides. There are three different types of these.
        • Pentoses (5)
          • Fructose
            • Molecular Formula- C6H1206
        • Hexoses (6)
          • Glucose
            • molecular formula-C6H12O6
            • Alfa
              • Hydroxyl group of C1 is below the plane of the ring
            • Beta
              • Hydroxyl group of C1 is above the plane of the ring
            • 1,4 and 6 are important positions in bonding monosaccharides together.
        • Trioses (3)
          • General formula- C6H1206
    • Polysaccharides
      • complex carbohydrates which often form very long chains. Via condensation a large number of monomers for together to form polymers
        • they are not sweet and are insoluable in water.
        • Important Polysaccharides
          • Starch, glycogen and cellulose.
            • Starch- is a polymer of Alfa glucose. Consists of two different arrangementsof starch
              • Amylose: is a 1,4 gylcosidic bond. These are then coiled in to a spiral shape and are then held in place by hydrogen. This forms long unbranched chains. 20% of starch is from amylose.
              • Amylopectin: links monomers using 1,4 glycosidic bonds and 1,6 gylcosidic bonds for branching. 80% of starch is normally in amylopectin form
            • Starch- good storage molecule:
              • 1.The molecules of both amylose and amylopectin are very compact
              • 2. It is osmotically inert and therefore will not interfere with the water potential
              • amylopectins branching nature create many terminal ends that are easily broken hydrolysed.
              • Large molecule- will not easily pass through the cell membrane meaning it can be retained within the cell
          • glycogen- can be found in animal and fungal cells, is stored in granules. Chains are more branched and shorter than amylopectin. It also has more terminal ends enabling faster hydrolysis when conditions demand
          • Cellulose-has a structural role. Is made up of Beta glucpse monomers which are joined together via `1,4 gylcosidic bonds. These molecules are flipped 180' every second monomer.
            • flipping effects:
              • The unbranched chains are straighter.
              • Hydrogen bonds can form cross-linkages between adjacent chains
            • The cellulose chains are grouped together in microfibrils, with each microfibril consisting of many cellulose molecules. Plant cell walls are then formed and are orientated into many planes in a lattice structure to further increase tensile stength.

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