• Starch, glycogen, and cellulose are examples of?polysaccharides
  • Polysaccharides are carbohydrate polymers; repeated chains of many monosaccharides?joined by glycosidic bonds?in a?condensation reaction
• Polysaccharides may be
  • Branched?or?unbranched
    • Being branched increases the rate at which a polysaccharide can be broken down
  • Straight?or?coiled
    • Being straight makes the molecules suitable for constructing cellular structures e.g. cellulose
    • Being coiled makes a molecule more compact and suitable for storage e.g. amylose in starch

• Starch?and?glycogen?are useful as storage polysaccharides because they are
  • Compact;?large quantities can be stored
  • Insoluble;?they?will have?no osmotic effect,?unlike glucose which would increase the solute concentration of a cell and causing water to move in by?osmosis

Starch

• Starch is the?storage?polysaccharide of?plants
  • It is stored as granules inside plant cells
  • Plants make glucose during?photosynthesis?and the molecules of glucose are joined to make the polysaccharide starch
• Starch is constructed from?two?different?polysaccharides
  • Amylose
    • Unbranched?helix-shaped?chain with 1,4 glycosidic bonds between α-glucose molecules
      • A helix is a spiral shape
    • The helix shape enables it to be more compact and thus more can be stored
  • Amylopectin
    • A?branched molecule?containing 1,4 glycosidic bonds between α-glucose molecules?and?1,6 glycosidic bonds
    • The branches result in many terminal glucose molecules that can be?easily hydrolysed?for use during cellular respiration or added to for storage

Amylose is a helix-shaped polysaccharide found in starch, the storage polysaccharide in plants

Amylopectin is a branched polysaccharide found in starch

Glycogen

• Glycogen is the?storage polysaccharide?of?animals and fungi
  • It is highly?branched?and not coiled
  • It contains both?1,4 and 1,6 glycosidic bonds
• Glycogen is?more branched than amylopectin
  • The branching provides more terminal glucose molecules which can either be?added to or removed by hydrolysis; this allows the?quick?storage or release of glucose to suit the demands of the cell
    • This is essential in animal cells as animals are very metabolically active
• Glycogen is compact which means that much can be stored in a small space
  • Liver and muscles cells have a high concentration of glycogen, present as?visible granules;?this enables a high?cellular respiration rate

Glycogen is a highly branched molecule used as a storage polysaccharide in animals and fungi

Summary of Storage Polysaccharides Table

Types of Carbohydrate Summary Table

• Starch?and?glycogen?are?storage?polysaccharides; they are adapted for this function by being
  • Compact
    • Large quantities can be stored
  • Insoluble
    • They will have?no osmotic effect?on cells, unlike glucose which can dissolve and raise the solute concentration of cell cytoplasm, causing water to move into cells by osmosis

Starch

• Starch is the?storage?polysaccharide of?plants;?it is stored as granules in?plastids
  • Plastids are?membrane-bound organelles?that can be found in plant cells
    • They have a specialised function, e.g. amyloplasts store starch grains and chloroplasts carry out photosynthesis
• The?amylose?in starch has a helical structure which makes it very compact, meaning that much can be stored in a small space
• The?amylopectin?in starch has branches that provide many terminal glucose molecules that can be?easily hydrolysed?for use during cellular respiration or added for storage

Glycogen

• Glycogen is the?storage?polysaccharide of?animals?and?fungi
• Glycogen is?more branched than amylopectin
  • The branching provides more terminal glucose molecules which can either be?added to or removed by hydrolysis; this allows the?quick?storage or release of glucose to suit the demands of the cell
    • This is essential in animal cells as animals are very metabolically active
• Glycogen is compact which means that much can be stored in a small space
  • Liver and muscles cells have a high concentration of glycogen, present as?visible granules;?this enables a high?cellular respiration rate