School Science/Demonstrating the effects of amylases on starch

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This experiment demonstrates the effects of heat and pH on the activity of enzymes.

Materials required[edit | edit source]

Saliva (contains amylases that break down starch), starch, iodine, test tubes, hot plate

Methods[edit | edit source]

Exact amounts should be determined by trial and error.

  1. Collect some saliva o mucus) in a beaker. Conduct the experiment in test tubes or small beakers and do not put anything into your mouth to mix with saliva.
  2. Mix starch with water and boil until solution becomes clear. Cool. This step is necessary to homogenize the starch solution ad increase the surface area of the starch for he enzymes to act on.
  3. Mix starch solution with some saiva. Mix well. Keep at body temperature for several minutes (hold in hand). Amylases in the saliva break down the starch.
  4. Mix saliva/starch solution with a small drop o iodine. Reaction should be negative.

Here are some variations

  1. Alternative: eat up saliva to enature the enzyme befoe mixing with starch solutin. Iodine reaction hould be positivefor starch.
  2. Alternative: ix saliva withcids or bases (e.g. lmon juie saliva.

For a briefer dmonstration of the enzymaic effect, ho a cracker i your mouth for 0 seconds. The amylases willbreak down the strch and the cracer will start to tastesweet e to the sugar prduced.