Polysaccharides

• What can polysaccharides be formed from?

  A large number of monosaccharides
• What are glycogen and starch formed from?

  Condensation of α-glucose
• What is cellulose formed from?

  Condensation of β-glucose
• What are the basic functions of glycogen, starch, and cellulose?

  Energy storage and structural support
• What is the biochemical test for starch?

  Using iodine solution
• How are polysaccharides formed?

  By joining monosaccharides through condensation reactions
• What happens to amylose during hydrolysis?

  It is broken down into α-glucose molecules
• What are the two types of polysaccharides made from α-glucose?

  • Amylose: Long, unbranched chain, compact structure
  • Amylopectin: Long, branched chain, easier breakdown
• Why is starch good for storage?

  It is insoluble in water and compact
• How does glycogen differ from starch?

  Glycogen has more side branches
• What is the structure of cellulose?

  Long, unbranched chains of β-glucose
• How do cellulose chains provide structural support?

  They form strong fibres called microfibrils
• What color indicates the presence of starch in the iodine test?

  Dark blue-black
• What happens to the sample if no starch is present in the iodine test?

  Changes from brown-orange to blue-black
• What are the main types of lipids and their functions?

  • Fats and oils: Energy storage and insulation
  • Phospholipids: Cell membranes
  • Steroids: Hormones
  • Carotenoids: Pigments
• What is the main form of energy storage in animals?

  Triglycerides
• What is the structure of a triglyceride?

  Glycerol linked to three fatty acids
• What distinguishes saturated fatty acids from unsaturated fatty acids?

  Saturated have only single bonds
• How does the structure of unsaturated fatty acids affect their properties?

  Double bonds create kinks in the chain
• What is the general structure of fatty acids?

  • Carboxyl group at one end
  • Basic hydrocarbon chain
  • Can be saturated or unsaturated
• What is the iodine test used for?

  To test for the presence of starch
• What does a positive iodine test indicate?

  Presence of starch in the sample
• What does a negative iodine test indicate?

  No starch is present in the sample
• What are the practice questions related to polysaccharides?

  1. Name the type of monomer for polysaccharides.
  2. Main energy storage in plants and animals.
  3. Solubility of starch and its storage advantage.
  4. Identify structures and their energy storage advantages.
  5. Major component of plant cell walls and its structure.
  6. Sketch and label a microfibril.
  7. Method to test for starch presence.