1.4 Starch, glycogen and cellulose

• The function of starch in plants is the storage of glucose.
• Starch is compact, as many glucose molecules are stored in a small space.
• Starch is insoluble, as it does not affect the osmotic balance of the cell, so water does not move in by osmosis.
• Starch is a large molecule, so it does not move out of the cell.
• Amylose is a type of starch that has an alpha helix straight chain .
• Amylopectin is a type of starch that has a branched structure.
• Amylose is composed of alpha glucose molecules joined together by alpha 1-4 glycosidic bonds, which forms a helix structure.
• Amylopectin, which is found in plants, is a highly branched alpha molecule joined together by some 1-4 bonds and some 1-6 branches.
• Amylopectin has more branch ends, so it can be hydrolysed by amylase more quickly than amylose.
• Amylose is few branched and highly compact, making it a good storage of glucose.
• To test for starch, iodine turns starch a blue/black colour.
• The 2 polysaccharides that make up starch are amylose and amylopectin
• Cellulose is insoluble in water due to its high molecular mass and strong intermolecular forces between chains
• what are starch, glycogen and cellulose?

  polysaccharides (within carbohydrates)
• name 3 polysaccharides


  starch, cellulose and glucose