Polysaccharides

• What are polysaccharides classified as?

  Carbohydrates
• What are polysaccharide molecules made from?

  Large numbers of monosaccharides
• How is a polysaccharide formed?

  By joining monosaccharides through condensation reactions
• What type of bond joins monosaccharides in polysaccharides?

  Glycosidic bonds
• What is an example of a polysaccharide formed from a-glucose?

  Amylose
• How can polysaccharides be broken down?

  By hydrolysis reactions
• What is amylose hydrolyzed into?

  a-glucose molecules
• What are the functions of polysaccharides like starch, glycogen, and cellulose?

  • Starch: Energy storage in plants
  • Glycogen: Energy storage in animals
  • Cellulose: Structural support in plant cell walls
• How do plants store excess glucose?

  As starch
• What happens when a plant needs more glucose for energy?

  It breaks down starch to release glucose
• What are the two polysaccharides that make up starch?

  Amylose and amylopectin
• Describe the structure of amylose.

  Long, unbranched chain of α-glucose
• What structural feature of amylose aids in storage?

  Its coiled structure
• What is the structure of amylopectin?

  Long, branched chain of α-glucose
• Why does amylopectin allow for quick glucose release?

  Its side branches allow enzyme access
• Why is starch insoluble in water?

  It doesn't affect water potential
• How do animal cells store excess glucose?

  As glycogen
• How does glycogen's structure compare to amylopectin?

  Glycogen has more side branches
• What is cellulose made of?

  Long, unbranched chains of β-glucose
• What do hydrogen bonds in cellulose form?

  Strong fibres called microfibrils
• What is the function of cellulose in plant cells?

  Provides structural support
• How can you test for the presence of starch?

  • Use iodine dissolved in potassium iodide
  • Positive test: dark blue-black color
  • Negative test: browny-orange color
• What color indicates the presence of starch in the iodine test?

  Dark blue-black
• What color indicates no starch in the iodine test?

  Browny-orange
• What should you include when describing the functions of starch in an exam?

  • Starch as an energy storage reserve
  • Avoid vague statements about containing starch
• What should you specify when describing polysaccharide structures?

  • Clearly state whether α-glucose or β-glucose is involved