1A.3 Polysaccharides

• what are polysaccharides?

  macromolecules formed of many monosaccharides joined together by glycosidic bonds during condensation reactions.
• what is starch used for?

  energy storage in plants, they store excess glucose as starch because its insoluble so has no osmotic effect.
• what is starch made of?

  alpha glucose and is a mixture of amylose and amylopectin.
• what is the structure of amylose?

  • compact/coiled so lots can be stored in a small place.• unbranched due to 1-4 glycosidic bonds.
• what is the structure of amylopectin?

  • branched structure due to 1-4 and 1-6 glycosidic bonds which means it can be easily and quickly hydrolysed (more surface area) when energy is needed.
• what is glycogen used for?

  energy storage in animals, they store extra glucose as glycogen for a short term because it's insoluble so has no osmotic effect.
• what is glycogen made of?

  alpha glucose.
• what is the structure of glycogen?

  • branched (more than amylopectin) due to 1-4 and 1-6 glycosidic bonds so can be easily hydrolysed (large surface area) so energy can be accessed quickly and easily.• insoluble - no osmotic effect.
• what is cellulose used for?

  structural support in plants.
• what is cellulose made of?

  beta glucose.
• what is the structure of cellulose?

  • unbranched due to only 1-4 glycosidic bonds.• each consecutive molecule is rotated 180 degrees to allow 1-4 bonds to form, this allows hydrogen bonds to form between the parallel chains which gives it high tensile strength.• arranged into microfibrils to add strength.
• what is the test for starch?

  iodine dissolved in potassium iodide.
• how do you conduct a test for starch? include results.

  • add iodine dissolved in potassium iodide to the test sample.• negative test - brown/orange.• positive test - blue/black.
• how does a coiled/compacted structure aid the function of polysaccharides?

  a lot can be stored in a small space.
• how does a large structure aid the function of polysaccharides?

  it wont diffuse out of cells.
• how does an insoluble structure aid the function of polysaccharides?

  it doesn't have an osmotic effect.
• how does a branched structure aid the function of polysaccharides?

  more surface area, meaning it can be easily hydrolysed when needed.
• Where is glycogen found?


  as small granules in the muscles and liver of animals