1.2 Carbohydrates

• 3 monosaccharides

  • glucose
  • fructose
  • galactose
• 3 disaccharides

  • sucrose
  • lactose
  • maltose
• 3 polysaccharides

  • glycogen
  • starch
  • cellulose
• alpha glucose- ABBA

  
• beta glucose-ABBA

  
• General formula for monosaccharides- (CH₂O)n
• Isomer- same number and types of atoms but arranged in a different structure
• general formula for disaccharide- C₁₂H₂₂O₁₁
• bond formed between 2 sugar units is called a glycosidic bond
• Sucrose

  • made from glucose and fructose
• Lactose

  • found in milk
  • made from glucose and galactose
• Maltose

  • made from 2 alpha glucoses
• All monosaccharides, maltose and lactose are reducing sugars apart from sucrose which is a non-reducing sugar
• hydrolysis is the reverse of a condensation reaction where water is added to the bond
• Amylose

  • monomer is alpha glucose- can be easily hydrolysed
  • coiled
  • compact, energy storage in plants
  • 1-4 glycosidic bonds between carbon 1 and 2- so is a long straight chain
  • coils held together by hydrogen bonds into a helical shape
  • insoluble- doesn't affect osmosis and doesn't move out of cells
• Amylopectin

  • monomer is alpha glucose
  • branched- easily hydrolysed by enzymes, leads to more glucose for respiration
  • compact, energy storage in plants
  • 1-4 and 1-6 glycosidic bonds between carbon 1 and 2 as well as carbon 1 and 6- so is a branched molecule
  • coils held together by hydrogen bonds
  • branched chain coils into a helical shape so it can store more in a small space
• Glycogen

  • monomer is alpha glucose- easily hydrolysed by enzymes, leads to more glucose for respiration
  • Highly branched
  • Compact, energy storage in animals
  • 1-4 and 1-6 glycosidic bonds between carbon 1 and 2 as well as carbon 1 and 6- branched molecule
  • coils held together by hydrogen bonds
  • insoluble- no affect on osmosis and doesn't move out of cells
• Cellulose

  • monomer is beta glucose, every other monomer is inverted
  • 1-4 glycosidic bonds form long straight chains
  • cellulose molecules run parallel to each other
  • hydrogen bonds between adjacent cellulose molecules- enables microfibrils to form, hydrogen bonds between microfibrils to form fibres
  • provides strength for structural support for cells