Carbohydrates

• Monomers join to make…


  Polymers
• Monosaccharides


  • Single sugar unit
  • Sweet and Soluble
  • Contain carbon, hydrogen & oxygen
• Classificaction of Monosaccharides 


  • Triose - 3 carbons
  • Penrose - 5 carbons
  • Hexose - 6 carbons
• What is this glucose molecule?

  Alpha

  
• What is this glucose molecule?

  Beta

  
• What is the difference between an alpha and beta glucose molecule?


  Beta has its -OH (Hydroxyl Group) above the ring, Alpha has it’s -OH below the ring
• Biological role of monisaccharides as an energy source


  • A large amount of energy is stored between the C-H bonds
  • This is released in the form of ATP
  • ATP is energy currency of the cell
• Biological role of monosaccharides as building blocks


  • Repeated glucose molecules form glycogen (when two alpha glucose molecules bond) and starch (when two beta glucose mol bond)
  • Ribose forms RNA
  • Deoxyribose forms DNA
• Structure of Disaccharides


  • Formed by 2 monosaccharides
  • The bond between the 2 monosaccharides is called a glycosidic bond
  • 2 alpha glucose make a maltose and water
• Polysaccharides


  • Polymers with 1000s of subunits of monomers
  • Repeated condensation reactions
  • Hydrolysis produces many molecules of monosaccharides
  • Polysaccharides are not sugars
• Starch


  • Chains of alpha glucose
  • Two molecules: Branches amylopectin (1-4 and 1-6 glycosidic bonds) Unbranched amylose (1-4 glycosidic bonds)
  • Insoluble in water
  • Hydrolysed to alpha glucose
  • Only in plant cells
• Glycogen


  • Branched chains of alpha glucose
  • Insoluble
  • Compact
  • Branches mean more ends are hydrolysed more rapidly
  • Stored as small granules in muscle or liver cells
• Cellulose


  • Monomers are beta glucose
  • Forms straight, unbranched chains
  • Chains run parallel, with hydrogen bonds linking them
  • Many weak bonds like hydrogen bonds strengthen the molecule
• Pros of Starch

  • Helical Structure - Compact and good for storage
  • Insoluble in water - Good for storage; doesn’t effect water potential
  • Made up of 2 polysaccharide: Amylose (Long, unbranched, coiled chain which is compact for storage - consists of 1 -4 bonds) and Amylopectin (Long branched chains that can be hydrolysed easily by enzymes - consists of 1-4 + 1-6 bonds)
• Pros of Glycogen

  • Alpha glucose
  • Long, branched, compact chain which can easily be hydrolysed to release glucose
  • Insoluble in water - doesn’t effect water potential
• Pros of Cellulose

  • Made up of Beta Glucose rotates 180° to make 1-4 bonds
  • Long straight unbranched chains
  • Hydrogen bonds between chains form microfibrils for structural support
  • Microfibrils group together to form fibres
  • Major component in cell walls that provide rigidity and allow turgidity of plant cells