Carbohydrates 3: Structural units

HideShow resource information
View mindmap
  • Carbohydrates 3: Structural units
    • Carbohydrate polymers - structural units
      • Beta-glucose can be boned together to form polymers through numerous condensation reactions
      • Alpha-glucose molecules can also be condensed to form coiled, spring-like chains
        • Beta-glucose molecules have a slightly different shape so when condensed form a long straight chain
      • These straight chain molecules can contain 10000 beta-glucose molecules, they are stronger tham the chains found in  amylose
        • these beta-glucose polymer chains are called cellulose chains
          • cellulose is only found in plants, it is the most abundant structural polysaccharide in nature
    • Cellulose
      • Cellulose fibres are arranged in a specific way to form plant cell walls
      • because the glucose monomers contain so may OH groups, many hydrogen bonds can form between them
      • about 60-70 cellulose molecules become cross-linked by hydrogen bonds to form bundles called microfibrils
        • these in turn are held together by more hydrogen bonds forming macrofibrils
      • The macrofibrils have great mechanical strength, they are embedded in a polysaccharide glue of substances called pectins, to form cell walls
    • Structure & function of plant cell walls
      • The cell walls around plant cell give great strength to each cell, supporting the whole plant
      • The arrangement of macrofibrils allows water to move through & along cells walls & can pass in/out of the cell easily
      • Water moving into plant cells does not cause them to burst - the wall prevents this and in turgid cells it helps to support the whole plant
      • The arrangement of macrofibrils in cell walls determines how cells can grow or change shape
        • e.g. guard cell walls have arrangement of macrofibrils that result in the opening/closing of stomata
      • Cell walls can be reinforced with other substances to provide extra support, or to make the walls waterproof
    • Other structural carbohydrates
      • A number of organisms use structural carbohydrate polymers
      • the polysaccharide chitin forms the exoskeleton of insects
      • the polysaccharide peptidoglycan is the basis of the cell walls found around most bacterial cells


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Biological molecules, organic chemistry and biochemistry resources »