Carbohydrates (mindmap)

Carbohydrates

1. Meaning ' hydrated carbon'

2. Made up of carbon, oxygen and hydrogen atoms.

3. Mono-saccharides

   • Mono- means 'one'
   • Glucose Fructose Galactose
     • There are 2 types of Glucose - Alpha and Beta
       • They are isomers / the same composition but different arrangement of structure (properties & functions may differ)
         • The difference is that once it form a ring in the A the C1 OH will point down in the B in will be up.
   • General formula = (CH^2O)n
     • n = 3-7
   • Simplest of carbohydrates
   • Sweet tasting, soluble substances.

4. Disaccharides

   • Di- means 'two'
   • Sucrose Maltose Lactose
     • Reducing sugars
       • Using water we can 'undo' the glycosidic bond and separate the sugar into 2 monosaccharides (hydrolisis)
     • Sucrose = glucose & fructose ( 1,4 glycosidic bond)
     • Lactose = Glucose & Galactose / 1,4 glycosidic bond
   • Formed when 2 monosaccharides react e.g A Glucose + A Glucose = Maltose
     • The C1 OH & C4 HO react to form H20 and a C-0-C bond (glycosidic bond)
       • Called 'condensation reaction'

5. Polysaccharides

   • Poly- means 'many'
   • Cellulose Starch Glycogen
     • Non-reducing sugars
     • Starch 2 forms : Amylose / amylopectin
       • Compact/ insoluble/ Has no osmotic effect / easily broken down by enzymes when required.
         • 1)Can be stored in smaller spaces
         • 2)Can be stored in water cells without being used up
         • 3)No net movement of water as a cause of starch storage - no cells bursting
         • 4)So plant can quickly respond to changes in glucose levels
       • Amylose - Simplest form of starch (30%)
         • 1000's of A-glucose in a straight chain (very tight coils) / insoluble- enzymes only 'nibble' at its ends
       • Amylopectin (70%)
         • Every 20 or so = branch of a glucose molecule bonded by a condensation reaction.
           • More ends to 'nibble' from = quicker reaction than amylose when there's a glucose deficit
     • Glycogen: Animal version of Amylopectin
       • Difference: branch every 6/7 glucose molecule (instead of 20) very compact
         • Energy store in animal livers
         • Animals more active - need more energy in shorter amount of time
     • Cellulose: B-glucose molecules linked by 1,4 glycosidic bonds
       • Every other glucose is upside down (alternating pattern)
         • Rigid, straight and compact structure
           • many of These end up forming microfibrils of cellulose
             • bonded together by hydrogen bonds of adjacent cellulose chains
               • H-H bonds are weak but in the masses are quite strong
     • Starch test : Iodine test
       • Add iodine dissolved in potassium iodide to sample.
         • If it turns black-blue there's starch in it.
           • If it stays orange there is no starch.
   • Polymers formed from repeated condensation reactions of monosaccharides

6. Greek prefixes = Mono/Di/Tri/Tetra/Penta/Hexa/Poly

   • Triose= carb with 3 carbons
     • E.g. Glyceraldehyde
       • C3H6O3
   • Tetrose = carb with 4 carbons
   • Pentose = 5 carbons
     • E.g. Ribose
       • C5H11O5
   • Hexose = 6 carbons
     • E.g. Glucose
       • C6H12O6

7. Ketose group (molecule with C=O bond in the middle of chain)

8. Aldose= C=O bond at the beggining

9. Hexoses and pentoses are long enough to form ring structures

   • Glucose: 1) C=O bond breaks 2) C5 loses H and bonds with O instead 3) Broken H bonds with C1

10. Benedict's Test

    • Heat sample with benedict's reagent
      • stays blue
        • No reducing sugars present
          • Heat new sample with HCL then neutralise with NaHCO3
            • Heat with Benedict's reagent
              • Goes green , yellow, orange, red or brown
                • Non-reducing sugars present
              • Stays blue
                • No non-reducing sugars present
      • goes green, yellow, orange, red or brown
        • Reducing sugars present