Biological molecules

• Define monomer. Give some examples.

  Smaller units that join together to form larger molecules.

  • monosaccharides (glucose, fructose, galactose)
  • amino acids
  • nucleotides
• Define polymer. Give some examples.

  Molecules formed when many monomers join together.

  • polysaccharides
  • proteins
  • DNA/RNA
• What happens in a condensation reaction?

  A chemical bond forms between 2 molecules and a molecule of water is produced.
• What happens in a hydrolysis reaction?

  A water molecule is used to break a chemical bond between 2 molecules.
• Name the 3 hexose monosaccharides

  All have the molecular formula C6H12O6.

  • glucose
  • fructose
  • galactose
• Name the type of bond formed when monosaccharides react.

  (1,4 or 1,6) glycosidic bond

  2 monomers = 1 chemical bond = disaccharide

  multiple monomers = multiple chemical bonds = polysaccharide
• Name 3 disaccharides. Describe how they form.

  Condensation reaction forms glycosidic bond between 2 monosaccharides.

  All have molecular formula C12H22O11.

  • maltose = glucose + glucose
  • sucrose = glucose + fructose
  • lactose = glucose + galactose
• Describe the structure and functions of starch. 


  storage polymer of a-glucose in plant cells.

  • insoluble = no osmotic effect on cells.
  • large = does not diffuse out of cells.
  • Made from amylose
  • 1-4 glycosidic bonds
  • helix with intermolecular H-bonds = compact
  • made from amylopectin
  • 1-4 and 1-6 glycosidic bonds
  • branched = many terminal ends for hydrolysis into glucose