carbohydrates

• carbohydrates are made of carbon, hydrogen and oxygen.
• disaccharides can be broken down into monosaccharides by enzymes.
• polysaccharides can be broken down into disaccharides or monosaccharides by enzymes.
• polysaccharides are long chains of glucose molecules joined together with glycosidic bonds
• starch is the main storage polysaccharide found in plants
• glucose is the most common monosaccharide found in plants and animals
• Other sugars

  sucrose= fructose + glucose

  lactose= galactose + glucose

  maltose= glucose + glucose
• Glycogen, cellulose and starch are all examples of polysaccharides.
• Glucose:

  • hexose monosaccharide
  • polar
  • soluble in water (means glucose is dissolved in cytosol of the cell)
• Condensation reactions:

  when two alpha glucose molecules are side by side, the two hydroxyl groups interact.
• Condensation reactions:

  • water molecule is produced
  • glycosidic bond forms between carbons 1 and 4
• Amylose:

  • formed by alpha glucose molecules
  • joined together by 1-4 glycosidic bonds
  • more compact and less soluble than glucose molecules
• Amylopectin:

  • also made by 1-4 glycosidic bonds between alpha glucose molecules but there are also some glycosidic bonds between carbons 1 and 6
  • branched structure
• The equivalent energy store molecule to starch (in plants) is glycogen in animals and fungi.
• Glycogen:

  • more branched than amylopectin
  • so more compact
  • ideal for storage
• Glycogen’s branched structure also means there are many free ends where glucose molecules can be added or removed. This speeds up the process of storing or releasing glucose molecules required by the cell.
• Hydrolysis reactions:

  To release glucose for respiration, starch or glycogen undergo hydrolysis reactions, requiring the addition of water molecules.
• Cellulose:

  • formed by alternate beta glucose molecules flipping upside down to bring the hydroxyl groups closer