CARBOHYDRATES

• Monomers


  Small, single units that act as the building blocks to create larger molecules
• Polymers


  Made up of many monomers, usually thousands, chemically bonded together
• Condensation reaction


  Monomers bond together, involves the removal of a water molecule

  
• Hydrolysis reaction


  The opposite of condensation, a water molecule is added between two bonded monomers to break the chemical bond

  
• Key Terms


  • Monomers
  • Polymers
  • Condensation reaction
  • Hydrolysis reaction
• Monosaccharides


  The monomers of carbohydrates, also known as sugars and are soluble in water
• Monosaccharides


  • Glucose
  • Galactose
  • Fructose

  
• Carbohydrates


  Key biological molecules that store energy and can provide structural support to plant cells

  
• All carbohydrates contain three elements: carbon, hydrogen and oxygen (CHO)
• General formula for a monosaccharide


  CnH2nOn, where n = the number of carbon atoms it contains

  
• Carbohydrate classification


  • Monosaccharides
  • Disaccharides
  • Polysaccharides

  
• Glucose


  A very important monosaccharide that can provide energy, be polymerised to form a structural support molecule (cellulose), or energy storage molecule (glycogen and starch)

  
• Isomer


  A compound that has the same formula, but the atoms are arranged differently
• Glucose isomers


  • α glucose
  • β glucose
• Condensation reaction creating a disaccharide

  A water molecule is removed, forming a glycosidic bond between two monosaccharides

  
• Disaccharides


  Two monosaccharides bonded together by a glycosidic bond, formed by a condensation reaction
• Hydrolysis reaction breaking down a disaccharide

  A water molecule is added to break the glycosidic bond

  
• Polysaccharides


  Polymers made up of many monosaccharides, created via condensation reactions

  
• Key polysaccharides


  • Starch
  • Glycogen
  • Cellulose

  
• Starch


  The major carbohydrate store in plants, made from excess glucose created during photosynthesis
• Structure of starch


  Polymer made up of α-glucose monomers joined by 1-4 and 1-6 glycosidic bonds

  
• Properties of starch


  • Insoluble due to large size, amylose is spiral-shaped for compact storage, amylopectin is branched for increased surface area for enzymes

  
• Glycogen


  The major carbohydrate storage molecule in animal cells, mainly stored in liver and muscle cells

  
• Structure of glycogen


  Polymer made up of α-glucose monomers joined by 1-4 and 1-6 glycosidic bonds, more branched than starch

  
• Properties of glycogen


  • Insoluble due to large size, highly branched structure provides large surface area for enzymes to act on, rapidly hydrolysed to provide glucose for high metabolic rate animals

  
• Cellulose


  The only polysaccharide made up of β-glucose monomers, provides structural strength in plant cell walls

  
• Structure of cellulose


  Unbranched polymer of β-glucose monomers joined by 1-4 glycosidic bonds, forms fibrils held together by hydrogen bonds

  
• Properties of cellulose


  • Insoluble due to large size, very strong due to hydrogen bonding between fibrils