Starch, Glycogen and Cellulose

• The rigidity of a plant cell wall is made up of long, straight, parallel chains, with hydrogen bonds between them. These chains are grouped into threads called microfibrils.
• Long, straight, parallel threads are further grouped into macrofibrils which are wound together to build the cell wall.
• Glycogen and starch both have important roles as storing molecules, and as sources of glucose for use in respiration 
• Glycogen and starch are formed by the condensation of alpha-glucose molecules
• Cellulose is formed by the condensation of beta-glucose molecules
• Describe the structure of glycogen

  • made of alpha glucose subunits joined by 1-4 glycosidic bonds
  • branches formed by 1-6 glycosidic bonds
  • made by liver and muscles
  • stored as granules in cytoplasm of cells
  • quickly hydrolysed when energy supplied is needed
• Describe the structure of starch?

  • insoluble sugar storage found in plants
  • stored in tubers/storage molecules known as amyloplasts
  • hydrolysed quickly when energy supply is needed
• Identify the properties of starch

  • alpha glucose
  • 1-4 glycosidic bonds in amylose
  • 1-4 and 1-6 in amylopectin
  • stores glucose
  • found in chloroplast
  • amylose - unbranched helix
  • amylopectin - branched molecule
  • helix compacts to fit lots of glucose
  • branched increases surface area
  • insoluble
• Identify the properties of cellulose

  • beta glucose
  • 1-4 glycosidic bonds
  • structure strength for cell wall
  • found in cell wall
  • long straight chains
  • many hydrogen bonds provides collective strength
  • insoluble
• Identify the properties of glycogen

  • alpha glucose
  • 1-4 and 1-6 glycosidic bonds
  • stores glucose
  • found in muscle and liver cells
  • highly branched
  • branched structure increases surface area for hydrolysis
  • insoluble