4. Biological molecules

• Glucose example: starch, glycogen and cellulose
• Carbohydrates: great fast source of energy (pasta, bread)

  • monomer: monosaccharides
  • contain (element): carbon hydrogen, oxygen
• Lipids (fats): great source of long term energy

  • monomer: fatty acid and glycerol
  • contain (element): carbon, hydrogen, oxygen
• Protein: muscle building, immune system, enzymes (meat, beans)

  • monomer: amino acid
  • contain (element): carbon, hydrogen, oxygen, nitrogen
• Nucleic acid (DNA, RNA): genetic material

  • monomer: nucleotides
  • contain: carbon, hydrogen, oxygen, nitrogen, phosphorus
• Food test:

  • starch - iodine: -ve result: brown, +ve result: blue/black
  • reducing sugar - benedict solution (heat solution before): -ve result: blue, +ve: brick red
  • proteins - biuret drops: -ve result: blue, +ve result: mauve
  • fats - ethanol with distilled water: -ve result: colourless, +ve result: milky white
  • vitamin C - DCPIP: +ve result: decolourisation
• DNA - Tigers Are Great Cats
• Double helix: a molecule of DNA that is made up of two strands of nucleotides held together by hydrogen bonds

  • each strand contain a chemical called base
  • cross-links between strands are formed by pairs of bases