Biological molecules

• What can biological molecules be broken down to fuel?

  Respiration
• What are carbohydrates made up of?

  Simple sugars
• What are proteins made up of?

  Amino acids
• What are lipids made up of?

  Fatty acids and glycerol
• Why is it important for the body to break down large, complex molecules like starch?

  To release energy for cellular processes
• What is the procedure to test for reducing sugars using Benedict's reagent?

  1. Add Benedict's reagent to the sample.
  2. Observe the color change; a colored precipitate indicates reducing sugars.
  3. The intensity of the color change indicates the concentration of reducing sugar.
• How do you test for non-reducing sugars?

  1. Add dilute hydrochloric acid and heat at 70°C.
  2. Neutralize with sodium hydrogencarbonate.
  3. Perform the Benedict's test; a colored precipitate indicates non-reducing sugars.
• What color change indicates the presence of starch when tested with iodine solution?

  Changes from brown-orange to dark blue-black
• What is the procedure for the emulsion test for lipids?

  1. Shake the test substance with ethanol until dissolved.
  2. Pour the solution into water.
  3. A milky emulsion indicates the presence of lipids.
• What is the procedure for the Biuret test for proteins?

  1. Add sodium hydroxide to make the solution alkaline.
  2. Add copper(II) sulfate solution.
  3. A purple color indicates the presence of proteins.
• What conclusion can be drawn if a solution turns purple after adding sodium hydroxide and copper(II) sulfate?

  Protein is present in the solution