Biology, 3: Biological molecules

• Carbohydrates are made up of what chemical elements?


  Carbon, hydrogen, oxygen
• Lipids are made up of what chemical elements?


  Carbon, hydrogen, oxygen
• Proteins are made up of what chemical elements?


  Carbon, hydrogen, oxygen, nitrogen
• What are carbohydrates made up of?


  Simple sugars, like glucose

  Simple sugars can link to form larger molecules

  In pairs to form sucrose

  Larger molecules like starch, glycogen, and cellulose
• What are proteins made up of?

  Amino acids

  20 types of amino acids

  Different ordering creates different proteins
• What are lipids made up of?


  1x glycerol

  3x fatty acids

  Important in forming cell membranes
• Testing for starch:

  • Benedict’s solution
  • Add solution into sample in test tube
  • Heat at 80°C for 5 minutes
  • Initial colour: Blue
  • Positive colour: Brick red
• Testing for protein:

  • Biuret solution
  • Add few drops to food sample
  • Initial colour: Blue
  • Positive colour: Purple
• Testing for starch:

  • Iodine solution
  • Add few drops to food sampel
  • Initial colour: Orange brown
  • Positive colour: Dark blue
• Testing for lipids:

  • Ethanol test
  • Mix sample with ethanol
  • Into test tube with water
  • Initial colour: Clear
  • Positive colour: Cloudy // emulsified
• Water is essential living organisms and is a solvent for chemical reactions.

  It is the main part of cytoplasm and plasma.