Carbohydrates

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  • carbohydrates
    • monosaccharides
      • trioses e.g glyceraldehyde
      • pentoses e.g ribose and deoxyribose
      • hexoses e.g glucose, hexose, fructose and galactose
        • GLUCOSE- 2 forms called isomers, a-glucose (OH group on C1 below the plane) and B-glucose (OH group on C1 is above the plane). Glucose is a 6 sided ring with C6 on a CH2OH branch.
        • GALACTOSE- 6 sided ring
        • FRUCTOSE- 5 sided ring (so CH2OH on C2 and HOH2C on C4)
      • formula = CnH2n0n
    • disaccharides
      • maltose
        • condensation reaction produces (eliminates) waterr
          • the bond that is formed is called a glycosidic bond which is covalent, therefore strong
            • it is a 1,4-glycosidic bond
    • reducing sugars
      • all monosaccharides and some disaccharides e.g maltose and lactose are reducing sugars
      • can give electrons away
      • test: add the sugar into Benedict's solution and heat together.  The solution should turn from blue to orange red. The orange red is described as a precipitate because it forms solid particles dispersed in the solution.
    • non reducing sugars
      • sucrose is the common non reducing sugar
      • test: make sure there are no reducing sugars in the sample, boil the sample with hydrochloric acid, this hydrolyses any sucrose present splitting it into glucose and fructose, cool the solution and add sodium hydrocarbonate solution to neutralise it, carry out test for reducing sugars then.
    • polysaccharides
      • these are energy storange molecules
      • polymers of monosaccharides joined together by glycosidic bonds
      • these are NOT sugars
      • they do not effect the water potential of a cell
      • STARCH
        • plant storage
        • made up of amylose and amylopectin
          • amylose- has 1,4-glycosidic bonds and made up of a-glucose
          • amylopectin has side branches due to 1,6-glycosidic bonds
        • found in : amyloplats, roots, leaves and seeds
        • broken down into glucose for respiration
      • GLYCOGEN
        • SIMILAR TO AMYLOPECTIN- made of 1,4-glycosidic bonds and 1,6-glycosidic bonds and made of a-glucoses
        • DIFFERENT TO AMYLOPECTIN- more side branches and shorter
        • more compact than starch
        • stored in the liver and muscle cells in animals
        • can be broken into a-glucose for respiration
      • CELLULOSE
        • found in cell walls, it is a structural protein
        • gives rigidity and strength to plant cells
        • it is a polymer of B-glucos, alternating B-glucose molecules are rotated by 180 degrees so a 1,4-glycosidic bond can form
        • will form long straight chains and although each molecule is weak they are strong together
        • cellulose chains lay side by side to create micro-fibrils, h-bonds form between hydroxide groups and H-groups of neighbouring chains, microfibrils bond to form macrofibrils, which form bundles called cellulose fibres which run in different directions to provide strength
      • CHITIN
        • used in exoskeletons of insects
        • structural polysaccharide
        • made from glucasamin subunits (similar to B-glucose except there is an amino acid on C2)
        • found in the cell walls of fungi
        • strong, flexible, lightweight and waterproof
        • forms microfibrils
  • polysaccharides
    • these are energy storange molecules
    • polymers of monosaccharides joined together by glycosidic bonds
    • these are NOT sugars
    • they do not effect the water potential of a cell
    • STARCH
      • plant storage
      • made up of amylose and amylopectin
        • amylose- has 1,4-glycosidic bonds and made up of a-glucose
        • amylopectin has side branches due to 1,6-glycosidic bonds
      • found in : amyloplats, roots, leaves and seeds
      • broken down into glucose for respiration
    • GLYCOGEN
      • SIMILAR TO AMYLOPECTIN- made of 1,4-glycosidic bonds and 1,6-glycosidic bonds and made of a-glucoses
      • DIFFERENT TO AMYLOPECTIN- more side branches and shorter
      • more compact than starch
      • stored in the liver and muscle cells in animals
      • can be broken into a-glucose for respiration
    • CELLULOSE
      • found in cell walls, it is a structural protein
      • gives rigidity and strength to plant cells
      • it is a polymer of B-glucos, alternating B-glucose molecules are rotated by 180 degrees so a 1,4-glycosidic bond can form
      • will form long straight chains and although each molecule is weak they are strong together
      • cellulose chains lay side by side to create micro-fibrils, h-bonds form between hydroxide groups and H-groups of neighbouring chains, microfibrils bond to form macrofibrils, which form bundles called cellulose fibres which run in different directions to provide strength
    • CHITIN
      • used in exoskeletons of insects
      • structural polysaccharide
      • made from glucasamin subunits (similar to B-glucose except there is an amino acid on C2)
      • found in the cell walls of fungi
      • strong, flexible, lightweight and waterproof
      • forms microfibrils

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