polysaccharides

• Polysaccharides can be broken down into their constituent monosaccharides by hydrolysis reactions.
• What is a polysaccharide?

  A polysaccharide is formed when more than two monosaccharides are joined together by condensation reactions.
• Starch

  Cells get energy from glucose. Plants store excess glucose as starch (when a plant needs more glucose for energy, it breaks down starch to release the glucose).
• Starch is a mixture of two polysaccharides of alpha-glucose — amylose and amylopectin
• What is amylose?


  Amylose is a long, unbranched chain of a-glucose.
• what are the properties of amylose?


  The angles of the glycosidic bonds give it a coiled structure, almost like a cylinder. This makes it compact
• Why do the side branches of amylopectin facilitate the breakdown of the molecule?


  They allow enzymes to access the glycosidic bonds easily
• What is the significance of the quick release of glucose from amylopectin?


  It provides a rapid source of energy
• What structural feature helps hold amylose in its helical structure?


  Hydrogen bonds between a-glucose molecules
• What is the primary function of amylopectin in plants?


  Energy storage
• How does the structure of amylopectin differ from that of amylose?


  Amylopectin is branched, while amylose is unbranched
• Starch is insoluble in water and doesn’t affect water potential

  , so it doesn’t cause water to enter cells by osmosis, which would make them swell. This makes it good for storage.
• Is starch soluble or insoluble/ why?


  insoluble - doesn't cause osmosis, no swelling, good for storage
• Glycogen


  A type of polysaccharide used by animal cells to store excess glucose, with a structure similar to amylopectin but with more side branches.
• Why do animals store glycogen?


  To release energy quickly for metabolic processes
• Why is glycogen good for storage?


  Because it's a compact molecule
• What is glycogen's structure similar to?


  amylopectin
• How do animals store excess glucose?

  Glycogen, a polysaccharide of alpha-glucose
• Cellulose


  A type of polysaccharide made of long, unbranched chains of beta-glucose molecules providing structural support for cells, especially in plant cell walls.
• Cellulose is made of


  Long, unbranched chains of beta-glucose
• Cellulose chains are formed by


  Beta-glucose molecules bonding
• Cellulose chains are linked together by


  Hydrogen bonds
• Function of cellulose


  Provides structural support for cells, e.g. in plant cell walls
• this structure is glycogen

  
• what structure is this

  cellulose

  
• If you want to test for the presence of starch in a sample, you’ll need to do the iodine test.

  Just add iodine dissolved in potassium iodide solution to the test sample. If there is starch present, the sample changes from browny-orange to a dark, blue-black colour

  
• what colour does the solution go from & to?

  browny orange to blue black