Carbohydrates

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  • Carbohydrates
    • Simple sugars
      • Functions in organisms
        • Energy source - released from glucose  during respiration
        • Energy store e.g Starch
        • Structure e.g. cellulose
      • Monosaccharides
        • 5 carbon monosaccharides are known as pentose sugars e.g. Deoxyribose
        • All are soluble in water, sweet tasting and form crystals
        • 3 carbon monosaccharides are known as triose sugars
        • 6 carbon monosaccharides are known as hexose sugars.
      • Glucose
        • Hexose sugar
        • Can be drawn in a chain or ring structure
        • In the ring structure there are two different isomers ALPHA glucose and BETA glucose
          • In alpha-glucose, the OH is below the plane of the ring
          • In the beta-structure, the OH IS above the plane of the ring
      • Joining and splitting
        • Two monosaccharides can be joined together in a CONDENSATION reaction
          • A covalent glycosidic bond is made with the elimination of water
        • The reverse reaction is a hydrolysis reaction which uses water to break the glycosidic bond
    • Carbohydrates make up a group of molecules containing carbon, hydrogen and oxygen in the ratio Cn(H2O)n
    • Energy storage
      • The breaking of glucose into simpler molecules of carbon dioxide and water in respiration releases energy in the form of ATP
        • Each step is driven by a specific enzyme. Animals and plants have enzymes that break down alpha-glucose only due to the different structure
      • A polysaccharide formed from alpha glucose is amylose
        • The long chains of amylose coil into a spring due to the formation of the glycosidic bonds
          • Iodine molecules can be trapped in the coils of the spring which causes it to change from yellow/brown to blue/black
        • The bond is called a 1,4-glycosidic bond
        • Insoluble in water
        • Hold glucose in chains so they can easily be broken off for respiration
      • In plants
        • Starch is a mixture of long, straight-chain amylose and branched amylopectin
          • Stored in chloroplasts and elsewhere in membrane-bound starch grains
      • In animals
        • Glycogen differs from starch in that the 1,4-glycosidic chains are shorter and have many more branches
          • More compact so forms glycogen granules - especially in liver and muscle cells
    • Structural units
      • Beta  glucose can be condensed to form long and straight chained polymer chains called cellulose chains
        • Cellulose is found in plants only
          • As the glucose monomers contain many OH groups, many hydrogen bonds can be formed
            • About 60 - 70 cellulose molecules become cross-linked to form microfibrils
              • These in turn can form hydrogen bonds to form macrofibrils which are embedded in pectin to form cell walls
      • Other structural carbohydrate polymers include chitin in exoskeletons and peptidoglycan in bacterial cell walls
      • Structure and function of cell wall
        • The wall prevents bursting and the cell becomes turgid instead, for support
        • Arrangement of macrofibrils allow water to move in and out of the cell
        • Can be reinforced with other substances to proved extra support  or to make the walls waterproof
        • The macrofibril arrangement in stomata result in the opening and closing of a stoma

Comments

arianator 4 life

wow awesome mindmap

arianator 4 life

wow awesome mindmap

Swallowtail

A concise Mind Map on carbohydrate structure  which is a topic found in many A level biology specifications. A good use of colour to separate the themes. Adding some images of the structures to the map after download will help make it even more memorable. Print the map out and then annotate with the functions of carbohydrates.

smilebright

thanks, good one

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