Unit4

• carbohydrates are made up of carbon, hydrogen and oxygen or CHO
• proteins are made up of carbon, hydrogen, oxygen and nitrogen (sometimes sulfur is also present)
• fats or lipids are made up of carbon, hydrogen and oxygen
• large molecules (polymers) are made from smaller molecules called monomers
• starch and glycogens monomer is glucose
• cellulose monomer is glucose
• protein monomer is amino acid
• fats and oils monomers are glycerol and fatty acids
• food test-

  • benedict's solution for reducing sugars
  • iodine solution for starch
  • biuret test for proteins
  • ethanol emulsion test for fats and oils
  • DCPIP solution for vitamin c
• test for glucose-

  • add benedict's solution into the sample solution in test tube
  • heat at 60-70°C for 5 minutes
  • positive test will show a color change from blue to orange to brick red
• test for protein-

  • add drops of biuret solution to the food sample
  • a positive test will show a color change from blue to violet
• test for lipids-

  • mix food sample with 2cm3 of ethanol and shake it
  • the ethanol is added to an equal volume of cold water
  • positive test will show a cloudy emulsion
• test for vitamin c-

  • add 1cm3 of DCPIP solution to a test tube
  • add a small amount of food sample as a solution
  • positive test will show blue color of the dye disappearing
• starch test-

  • add a drop of iodine solution into the food to be tested
  • positive test will show a color change from brown to blue black
• Describe the structure of DNA as:

  • a-two strands coiled together to form a double helix
  • b-each strand contains chemicals called bases
  • c-cross-links between the strands are formed by pairs of bases
  • d-the bases always pair up in the same way: A with T. and C with G
• adenine and thymine, cytosine and guanine